diff --git a/packages/keyring-api/CHANGELOG.md b/packages/keyring-api/CHANGELOG.md
index c7b3cfff3..e9eec2723 100644
--- a/packages/keyring-api/CHANGELOG.md
+++ b/packages/keyring-api/CHANGELOG.md
@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **BREAKING**: Add required `rawAmount` field to `Balance` and `FungibleAssetAmount` types for precision in balance calculations ([#426](https://github.com/MetaMask/accounts/pull/426))
 - Refine `EthAddressStruct` in order to make it compatible with the `Hex` type from `@metamask/utils` ([#405](https://github.com/MetaMask/accounts/pull/405))
 
 ## [21.3.0]
diff --git a/packages/keyring-api/src/api/asset.test-d.ts b/packages/keyring-api/src/api/asset.test-d.ts
index f150b7210..209f25b8d 100644
--- a/packages/keyring-api/src/api/asset.test-d.ts
+++ b/packages/keyring-api/src/api/asset.test-d.ts
@@ -2,37 +2,54 @@ import { expectAssignable, expectNotAssignable } from 'tsd';
 
 import type { Asset } from './asset';
 
+// Valid fungible asset
 expectAssignable<Asset>({
   fungible: true,
   type: 'eip155:1/slip44:60',
   unit: 'ETH',
   amount: '0.01',
+  rawAmount: '10000000000000000',
 });
 
+// Valid non-fungible asset
 expectAssignable<Asset>({
   fungible: false,
   id: 'hedera:mainnet/nft:0.0.55492/12',
 });
 
+// Missing rawAmount for fungible asset
 expectNotAssignable<Asset>({
   fungible: true,
   type: 'eip155:1/slip44:60',
   unit: 'ETH',
+  amount: '0.01',
+});
+
+// Fungible asset with non-fungible id field
+expectNotAssignable<Asset>({
+  fungible: true,
+  type: 'eip155:1/slip44:60',
+  unit: 'ETH',
+  amount: '0.01',
+  rawAmount: '10000000000000000',
   id: 'hedera:mainnet/nft:0.0.55492/12',
 });
 
+// Non-fungible asset with unit field
 expectNotAssignable<Asset>({
   fungible: false,
   id: 'hedera:mainnet/nft:0.0.55492/12',
   unit: 'ETH',
 });
 
+// Non-fungible asset with type and unit
 expectNotAssignable<Asset>({
   fungible: false,
   type: 'eip155:1/slip44:60',
   unit: 'ETH',
 });
 
+// Fungible asset with id instead of type
 expectNotAssignable<Asset>({
   fungible: true,
   id: 'hedera:mainnet/nft:0.0.55492/12',
diff --git a/packages/keyring-api/src/api/asset.test.ts b/packages/keyring-api/src/api/asset.test.ts
index 572086554..c2477820b 100644
--- a/packages/keyring-api/src/api/asset.test.ts
+++ b/packages/keyring-api/src/api/asset.test.ts
@@ -6,7 +6,7 @@ describe('AssetStruct', () => {
   it.each([
     // Missing `fungible`
     { asset: {}, expected: false },
-    // Valid
+    // Valid non-fungible asset
     {
       asset: {
         fungible: false,
@@ -14,19 +14,19 @@ describe('AssetStruct', () => {
       },
       expected: true,
     },
-    // Missing `unit` and `amount`
+    // Missing `unit`, `amount`, and `rawAmount`
     { asset: { fungible: true, type: 'eip155:1/slip44:60' }, expected: false },
-    // Missing `amount`
+    // Missing `amount` and `rawAmount`
     {
       asset: { fungible: true, type: 'eip155:1/slip44:60', unit: 'ETH' },
       expected: false,
     },
-    // Missing `unit`
+    // Missing `unit` and `rawAmount`
     {
       asset: { fungible: true, type: 'eip155:1/slip44:60', amount: '0.01' },
       expected: false,
     },
-    // Valid
+    // Missing `rawAmount`
     {
       asset: {
         fungible: true,
@@ -34,6 +34,17 @@ describe('AssetStruct', () => {
         unit: 'ETH',
         amount: '0.01',
       },
+      expected: false,
+    },
+    // Valid fungible asset
+    {
+      asset: {
+        fungible: true,
+        type: 'eip155:1/slip44:60',
+        unit: 'ETH',
+        amount: '0.01',
+        rawAmount: '10000000000000000',
+      },
       expected: true,
     },
   ])('returns $expected for is($asset, AssetStruct)', ({ asset, expected }) => {
diff --git a/packages/keyring-api/src/api/asset.ts b/packages/keyring-api/src/api/asset.ts
index 154a33905..0f68e3cd4 100644
--- a/packages/keyring-api/src/api/asset.ts
+++ b/packages/keyring-api/src/api/asset.ts
@@ -16,14 +16,21 @@ import {
  */
 export const FungibleAssetAmountStruct = object({
   /**
-   * Asset unit.
+   * Asset unit (symbol).
    */
   unit: string(),
 
   /**
-   * Asset amount.
+   * The human-readable asset amount with decimals applied (e.g., "1.5" for 1.5 SOL).
+   * This is kept for backward compatibility with existing consumers.
    */
   amount: StringNumberStruct,
+
+  /**
+   * The raw blockchain balance without decimals applied (e.g., "1500000000" for 1.5 SOL).
+   * This provides precision for calculations using BigInt/BigNumber.
+   */
+  rawAmount: string(),
 });
 
 /**
@@ -83,6 +90,7 @@ export const NonFungibleAssetStruct = object({
  *   type: 'eip155:1/slip44:60',
  *   unit: 'ETH',
  *   amount: '0.01',
+ *   rawAmount: '10000000000000000',
  * }
  * ```
  *
diff --git a/packages/keyring-api/src/api/balance.test-d.ts b/packages/keyring-api/src/api/balance.test-d.ts
index ccb0cc662..de2734bdb 100644
--- a/packages/keyring-api/src/api/balance.test-d.ts
+++ b/packages/keyring-api/src/api/balance.test-d.ts
@@ -2,18 +2,86 @@ import { expectAssignable, expectNotAssignable } from 'tsd';
 
 import type { Balance } from './balance';
 
-expectAssignable<Balance>({ amount: '1.0', unit: 'ETH' });
-expectAssignable<Balance>({ amount: '0.1', unit: 'BTC' });
-expectAssignable<Balance>({ amount: '.1', unit: 'gwei' });
-expectAssignable<Balance>({ amount: '.1', unit: 'wei' });
-expectAssignable<Balance>({ amount: '1.', unit: 'sat' });
+// Valid balances with all required fields
+expectAssignable<Balance>({
+  amount: '1.0',
+  unit: 'ETH',
+  rawAmount: '1000000000000000000',
+});
+expectAssignable<Balance>({
+  amount: '0.1',
+  unit: 'BTC',
+  rawAmount: '10000000',
+});
+expectAssignable<Balance>({
+  amount: '.1',
+  unit: 'gwei',
+  rawAmount: '100000000',
+});
+expectAssignable<Balance>({
+  amount: '.1',
+  unit: 'wei',
+  rawAmount: '100000000',
+});
+expectAssignable<Balance>({
+  amount: '1.',
+  unit: 'sat',
+  rawAmount: '100000000',
+});
 
-expectNotAssignable<Balance>({ amount: 1, unit: 'ETH' });
-expectNotAssignable<Balance>({ amount: true, unit: 'ETH' });
-expectNotAssignable<Balance>({ amount: undefined, unit: 'ETH' });
-expectNotAssignable<Balance>({ amount: null, unit: 'ETH' });
+// Missing rawAmount
+expectNotAssignable<Balance>({ amount: '1.0', unit: 'ETH' });
 
-expectNotAssignable<Balance>({ amount: '1.0', unit: 1 });
-expectNotAssignable<Balance>({ amount: '1.0', unit: true });
-expectNotAssignable<Balance>({ amount: '1.0', unit: undefined });
-expectNotAssignable<Balance>({ amount: '1.0', unit: null });
+// Invalid amount types
+expectNotAssignable<Balance>({
+  amount: 1,
+  unit: 'ETH',
+  rawAmount: '1000000000000000000',
+});
+expectNotAssignable<Balance>({
+  amount: true,
+  unit: 'ETH',
+  rawAmount: '1000000000000000000',
+});
+expectNotAssignable<Balance>({
+  amount: undefined,
+  unit: 'ETH',
+  rawAmount: '1000000000000000000',
+});
+expectNotAssignable<Balance>({
+  amount: null,
+  unit: 'ETH',
+  rawAmount: '1000000000000000000',
+});
+
+// Invalid unit types
+expectNotAssignable<Balance>({
+  amount: '1.0',
+  unit: 1,
+  rawAmount: '1000000000000000000',
+});
+expectNotAssignable<Balance>({
+  amount: '1.0',
+  unit: true,
+  rawAmount: '1000000000000000000',
+});
+expectNotAssignable<Balance>({
+  amount: '1.0',
+  unit: undefined,
+  rawAmount: '1000000000000000000',
+});
+expectNotAssignable<Balance>({
+  amount: '1.0',
+  unit: null,
+  rawAmount: '1000000000000000000',
+});
+
+// Invalid rawAmount types
+expectNotAssignable<Balance>({ amount: '1.0', unit: 'ETH', rawAmount: 1 });
+expectNotAssignable<Balance>({ amount: '1.0', unit: 'ETH', rawAmount: true });
+expectNotAssignable<Balance>({
+  amount: '1.0',
+  unit: 'ETH',
+  rawAmount: undefined,
+});
+expectNotAssignable<Balance>({ amount: '1.0', unit: 'ETH', rawAmount: null });
diff --git a/packages/keyring-api/src/api/balance.test.ts b/packages/keyring-api/src/api/balance.test.ts
index 27ce466fb..4bff25248 100644
--- a/packages/keyring-api/src/api/balance.test.ts
+++ b/packages/keyring-api/src/api/balance.test.ts
@@ -5,20 +5,62 @@ import { BalanceStruct } from './balance';
 describe('BalanceStruct', () => {
   it.each([
     // Valid
-    { balance: { amount: '1.0', unit: 'ETH' }, expected: true },
-    { balance: { amount: '0.1', unit: 'BTC' }, expected: true },
+    {
+      balance: { amount: '1.0', unit: 'ETH', rawAmount: '1000000000000000000' },
+      expected: true,
+    },
+    {
+      balance: { amount: '0.1', unit: 'BTC', rawAmount: '10000000' },
+      expected: true,
+    },
     // Missing amount
-    { balance: { unit: 'ETH' }, expected: false },
+    {
+      balance: { unit: 'ETH', rawAmount: '1000000000000000000' },
+      expected: false,
+    },
     // Missing unit
-    { balance: { amount: '1.0' }, expected: false },
+    {
+      balance: { amount: '1.0', rawAmount: '1000000000000000000' },
+      expected: false,
+    },
+    // Missing rawAmount
+    { balance: { amount: '1.0', unit: 'ETH' }, expected: false },
     // Invalid amount type
-    { balance: { amount: 1, unit: 'ETH' }, expected: false },
-    { balance: { amount: true, unit: 'ETH' }, expected: false },
-    { balance: { amount: null, unit: 'ETH' }, expected: false },
+    {
+      balance: { amount: 1, unit: 'ETH', rawAmount: '1000000000000000000' },
+      expected: false,
+    },
+    {
+      balance: { amount: true, unit: 'ETH', rawAmount: '1000000000000000000' },
+      expected: false,
+    },
+    {
+      balance: { amount: null, unit: 'ETH', rawAmount: '1000000000000000000' },
+      expected: false,
+    },
     // Invalid unit type
-    { balance: { amount: '1.0', unit: 1 }, expected: false },
-    { balance: { amount: '1.0', unit: true }, expected: false },
-    { balance: { amount: '1.0', unit: null }, expected: false },
+    {
+      balance: { amount: '1.0', unit: 1, rawAmount: '1000000000000000000' },
+      expected: false,
+    },
+    {
+      balance: { amount: '1.0', unit: true, rawAmount: '1000000000000000000' },
+      expected: false,
+    },
+    {
+      balance: { amount: '1.0', unit: null, rawAmount: '1000000000000000000' },
+      expected: false,
+    },
+    // Invalid rawAmount type
+    { balance: { amount: '1.0', unit: 'ETH', rawAmount: 1 }, expected: false },
+    {
+      balance: { amount: '1.0', unit: 'ETH', rawAmount: true },
+      expected: false,
+    },
+    {
+      balance: { amount: '1.0', unit: 'ETH', rawAmount: null },
+      expected: false,
+    },
   ])(
     'returns $expected for is($balance, BalanceStruct)',
     ({ balance, expected }) => {
diff --git a/packages/keyring-api/src/api/balance.ts b/packages/keyring-api/src/api/balance.ts
index 32b7573f8..cc636c22e 100644
--- a/packages/keyring-api/src/api/balance.ts
+++ b/packages/keyring-api/src/api/balance.ts
@@ -3,8 +3,20 @@ import type { Infer } from '@metamask/superstruct';
 import { string } from '@metamask/superstruct';
 
 export const BalanceStruct = object({
+  /**
+   * The human-readable balance amount with decimals applied (e.g., "1.5" for 1.5 SOL).
+   * This is kept for backward compatibility with existing consumers.
+   */
   amount: StringNumberStruct,
+  /**
+   * The token/asset symbol or unit (e.g., "SOL", "TRX").
+   */
   unit: string(),
+  /**
+   * The raw blockchain balance without decimals applied (e.g., "1500000000" for 1.5 SOL).
+   * This provides precision for calculations using BigInt/BigNumber.
+   */
+  rawAmount: string(),
 });
 
 export type Balance = Infer<typeof BalanceStruct>;
diff --git a/packages/keyring-api/src/api/transaction.test-d.ts b/packages/keyring-api/src/api/transaction.test-d.ts
index 0b5d8e2e2..9bf7e062d 100644
--- a/packages/keyring-api/src/api/transaction.test-d.ts
+++ b/packages/keyring-api/src/api/transaction.test-d.ts
@@ -32,6 +32,7 @@ expectAssignable<Transaction>({
         type: 'eip155:1/slip44:60',
         unit: 'ETH',
         amount: '0.0001',
+        rawAmount: '100000000000000',
       },
     },
     {
@@ -41,6 +42,7 @@ expectAssignable<Transaction>({
         type: 'eip155:1/slip44:60',
         unit: 'ETH',
         amount: '0.0001',
+        rawAmount: '100000000000000',
       },
     },
   ],
@@ -62,6 +64,7 @@ expectAssignable<Transaction>({
         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
         unit: 'BTC',
         amount: '0.002',
+        rawAmount: '200000',
       },
     },
     {
@@ -80,6 +83,7 @@ expectAssignable<Transaction>({
         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
         unit: 'BTC',
         amount: '0.001',
+        rawAmount: '100000',
       },
     },
     {
@@ -98,6 +102,7 @@ expectAssignable<Transaction>({
         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
         unit: 'BTC',
         amount: '0.001',
+        rawAmount: '100000',
       },
     },
   ],
diff --git a/packages/keyring-api/src/api/transaction.ts b/packages/keyring-api/src/api/transaction.ts
index 3d3f38566..9fc1070a8 100644
--- a/packages/keyring-api/src/api/transaction.ts
+++ b/packages/keyring-api/src/api/transaction.ts
@@ -19,6 +19,7 @@ import type { Paginated } from './pagination';
  *     type: 'eip155:1/slip44:60',
  *     unit: 'ETH',
  *     amount: '0.01',
+ *     rawAmount: '10000000000000000',
  *   },
  * },
  * ```
@@ -211,6 +212,7 @@ export const TransactionEventStruct = object({
  *         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
  *         unit: 'BTC',
  *         amount: '0.1',
+ *         rawAmount: '10000000',
  *       },
  *     },
  *   ],
@@ -222,6 +224,7 @@ export const TransactionEventStruct = object({
  *         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
  *         unit: 'BTC',
  *         amount: '0.1',
+ *         rawAmount: '10000000',
  *       },
  *     },
  *     {
@@ -231,6 +234,7 @@ export const TransactionEventStruct = object({
  *         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
  *         unit: 'BTC',
  *         amount: '0.1',
+ *         rawAmount: '10000000',
  *       },
  *     },
  *   ],
@@ -242,6 +246,7 @@ export const TransactionEventStruct = object({
  *         type: 'bip122:000000000019d6689c085ae165831e93/slip44:0',
  *         unit: 'BTC',
  *         amount: '0.1',
+ *         rawAmount: '10000000',
  *       },
  *     },
  *   ],
diff --git a/packages/keyring-api/src/events.test-d.ts b/packages/keyring-api/src/events.test-d.ts
index 72eee185f..2abc355f1 100644
--- a/packages/keyring-api/src/events.test-d.ts
+++ b/packages/keyring-api/src/events.test-d.ts
@@ -209,6 +209,7 @@ expectAssignable<KeyringEventPayload<KeyringEvent.AccountBalancesUpdated>>({
       'bip122:000000000019d6689c085ae165831e93/slip44:0': {
         amount: '0.0001',
         unit: 'BTC',
+        rawAmount: '10000',
       },
     },
   },
@@ -220,6 +221,7 @@ expectNotAssignable<KeyringEventPayload<KeyringEvent.AccountBalancesUpdated>>({
     'bip122:000000000019d6689c085ae165831e93/slip44:0': {
       amount: '0.0001',
       unit: 'BTC',
+      rawAmount: '10000',
     },
   },
 });
@@ -230,6 +232,7 @@ expectNotAssignable<KeyringEventPayload<KeyringEvent.AccountBalancesUpdated>>({
     'bip122:000000000019d6689c085ae165831e93/slip44:0': {
       amount: '0.0001',
       unit: 'BTC',
+      rawAmount: '10000',
     },
   },
 });
@@ -241,6 +244,19 @@ expectNotAssignable<KeyringEventPayload<KeyringEvent.AccountBalancesUpdated>>({
       bitcoin: {
         amount: '0.0001',
         unit: 'BTC',
+        rawAmount: '10000',
+      },
+    },
+  },
+});
+
+expectNotAssignable<KeyringEventPayload<KeyringEvent.AccountBalancesUpdated>>({
+  balances: {
+    '11027d05-12f8-4ec0-b03f-151d86a8089e': {
+      'bip122:000000000019d6689c085ae165831e93/slip44:0': {
+        // Missing `rawAmount`
+        amount: '0.0001',
+        unit: 'BTC',
       },
     },
   },
diff --git a/packages/keyring-snap-bridge/src/SnapKeyring.test.ts b/packages/keyring-snap-bridge/src/SnapKeyring.test.ts
index 7db510cfb..4b0e446f6 100644
--- a/packages/keyring-snap-bridge/src/SnapKeyring.test.ts
+++ b/packages/keyring-snap-bridge/src/SnapKeyring.test.ts
@@ -681,6 +681,7 @@ describe('SnapKeyring', () => {
               'bip122:000000000019d6689c085ae165831e93/slip44:0': {
                 amount: '0.1',
                 unit: 'BTC',
+                rawAmount: '10000000',
               },
             },
           },
@@ -706,6 +707,7 @@ describe('SnapKeyring', () => {
           'bip122:000000000019d6689c085ae165831e93/slip44:0': {
             amount: '0.1',
             unit: 'BTC',
+            rawAmount: '10000000',
           },
         };
         const event: AccountBalancesUpdatedEventPayload = {
@@ -761,6 +763,7 @@ describe('SnapKeyring', () => {
                       type: 'eip155:1/slip44:60',
                       unit: 'ETH',
                       amount: '0.0001',
+                      rawAmount: '100000000000000',
                     },
                   },
                   {
@@ -770,6 +773,7 @@ describe('SnapKeyring', () => {
                       type: 'eip155:1/slip44:60',
                       unit: 'ETH',
                       amount: '0.0001',
+                      rawAmount: '100000000000000',
                     },
                   },
                 ],
@@ -813,6 +817,7 @@ describe('SnapKeyring', () => {
                   type: 'eip155:1/slip44:60',
                   unit: 'ETH',
                   amount: '0.0001',
+                  rawAmount: '100000000000000',
                 },
               },
               {
@@ -822,6 +827,7 @@ describe('SnapKeyring', () => {
                   type: 'eip155:1/slip44:60',
                   unit: 'ETH',
                   amount: '0.0001',
+                  rawAmount: '100000000000000',
                 },
               },
             ],
diff --git a/packages/keyring-snap-client/src/KeyringClient.test.ts b/packages/keyring-snap-client/src/KeyringClient.test.ts
index 71ed612b3..67d4b18f1 100644
--- a/packages/keyring-snap-client/src/KeyringClient.test.ts
+++ b/packages/keyring-snap-client/src/KeyringClient.test.ts
@@ -431,6 +431,7 @@ describe('KeyringClient', () => {
                   type: 'eip155:1/slip44:60',
                   unit: 'ETH',
                   amount: 'invalid-amount', // Should be a numeric string
+                  rawAmount: '100000000000000',
                 },
               },
             ],
@@ -554,6 +555,7 @@ describe('KeyringClient', () => {
         [assets[0] as string]: {
           amount: '1234',
           unit: 'sat',
+          rawAmount: '1234',
         },
       };
 
@@ -579,6 +581,7 @@ describe('KeyringClient', () => {
         [assets[0] as string]: {
           amount: 1234, // Should be a `StringNumber`
           unit: 'sat',
+          rawAmount: '1234',
         },
       };
 
@@ -597,6 +600,7 @@ describe('KeyringClient', () => {
         [assets[0] as string]: {
           amount: 'not-a-string-number', // Should be a `StringNumber`
           unit: 'sat',
+          rawAmount: '1234',
         },
       };
 
@@ -605,6 +609,25 @@ describe('KeyringClient', () => {
         'At path: bip122:000000000019d6689c085ae165831e93/slip44:0.amount -- Expected a value of type `StringNumber`, but received: `"not-a-string-number"`',
       );
     });
+
+    it('throws an error because the rawAmount is missing', async () => {
+      const assets: CaipAssetType[] = [
+        'bip122:000000000019d6689c085ae165831e93/slip44:0',
+      ];
+      const id = '1617ea08-d4b6-48bf-ba83-901ef1e45ed7';
+      const expectedResponse = {
+        [assets[0] as string]: {
+          amount: '1234',
+          unit: 'sat',
+          // Missing rawAmount
+        },
+      };
+
+      mockSender.send.mockResolvedValue(expectedResponse);
+      await expect(client.getAccountBalances(id, assets)).rejects.toThrow(
+        'At path: bip122:000000000019d6689c085ae165831e93/slip44:0.rawAmount -- Expected a string, but received: undefined',
+      );
+    });
   });
 
   describe('resolveAccountAddress', () => {