diff --git a/modules/bitgo/test/v2/unit/wallet.ts b/modules/bitgo/test/v2/unit/wallet.ts
index 60b563514a..dd418def04 100644
--- a/modules/bitgo/test/v2/unit/wallet.ts
+++ b/modules/bitgo/test/v2/unit/wallet.ts
@@ -4643,6 +4643,13 @@ describe('V2 Wallet:', function () {
       });
     });
 
+    const exampleAttestation = {
+      signature: 'sig',
+      credentialId: 'cred',
+      clientDataJSON: 'cdj',
+      authenticatorData: 'ad',
+    };
+
     describe('getUserKeyAndSignTssTransaction', function () {
       ['eddsa', 'ecdsa'].forEach((keyCurve: string) => {
         describe(keyCurve, () => {
@@ -4681,6 +4688,29 @@ describe('V2 Wallet:', function () {
 
             getKeysStub.calledOnce.should.be.true();
             signTransactionStub.calledOnce.should.be.true();
+            signTransactionStub.firstCall.args[0].should.not.have.property('attestation');
+          });
+
+          it('should forward the attestation to signTransaction', async function () {
+            getKeysStub.resolves([
+              {
+                commonKeychain: 'test',
+                id: '',
+                pub: '',
+                type: 'tss',
+                encryptedPrv:
+                  '{"iv":"15FsbDVI1zG9OggD8YX+Hg==","v":1,"iter":10000,"ks":256,"ts":64,"mode":"ccm","adata":"","cipher":"aes","salt":"hHbNH3Sz/aU=","ct":"WoNVKz7afiRxXI2w/YkzMdMyoQg/B15u1Q8aQgi96jJZ9wk6TIaSEc6bXFH3AHzD9MdJCWJQUpRhoQc/rgytcn69scPTjKeeyVMElGCxZdFVS/psQcNE+lue3//2Zlxj+6t1NkvYO+8yAezSMRBK5OdftXEjNQI="}',
+              },
+            ]);
+
+            await wallet.getUserKeyAndSignTssTransaction({
+              walletPassphrase: TestBitGo.V2.TEST_ETH_WALLET_PASSPHRASE as string,
+              txRequestId: 'id',
+              attestation: exampleAttestation,
+            });
+
+            signTransactionStub.calledOnce.should.be.true();
+            signTransactionStub.firstCall.args[0].should.have.property('attestation', exampleAttestation);
           });
 
           it('should throw if the keychain doesnt have the encryptedKey', async function () {
@@ -4770,6 +4800,49 @@ describe('V2 Wallet:', function () {
         sandbox.assert.calledOnce(getUserKeyAndSignTssTxSpy);
         signedTx.should.deepEqual(exampleSignedTx);
       });
+
+      it('should forward the attestation to first-round signing only, not the lite submit', async function () {
+        const deleteSignatureSharesSpy = sandbox.stub(TssUtils.prototype, 'deleteSignatureShares');
+        const getUserKeyAndSignTssTxSpy = sandbox.stub(tssSolWallet, 'getUserKeyAndSignTssTransaction');
+        getUserKeyAndSignTssTxSpy.resolves(exampleSignedTx);
+        const submitTxSpy = sandbox.stub(tssSolWallet, 'submitTransaction');
+        submitTxSpy.resolves(exampleSignedTx);
+
+        await tssSolWallet.signAndSendTxRequest({
+          walletPassphrase: 'passphrase',
+          txRequestId: 'id',
+          isTxRequestFull: false,
+          attestation: exampleAttestation,
+        });
+
+        sandbox.assert.callOrder(deleteSignatureSharesSpy, getUserKeyAndSignTssTxSpy, submitTxSpy);
+        sandbox.assert.calledOnce(getUserKeyAndSignTssTxSpy);
+        sandbox.assert.calledWithExactly(getUserKeyAndSignTssTxSpy, {
+          walletPassphrase: 'passphrase',
+          txRequestId: 'id',
+          attestation: exampleAttestation,
+        });
+        sandbox.assert.calledOnce(submitTxSpy);
+        sandbox.assert.calledWithExactly(submitTxSpy, { txRequestId: 'id' });
+      });
+
+      it('should not send an attestation key when none is provided', async function () {
+        sandbox.stub(TssUtils.prototype, 'deleteSignatureShares');
+        const getUserKeyAndSignTssTxSpy = sandbox.stub(tssSolWallet, 'getUserKeyAndSignTssTransaction');
+        getUserKeyAndSignTssTxSpy.resolves(exampleSignedTx);
+
+        await tssSolWallet.signAndSendTxRequest({
+          walletPassphrase: 'passphrase',
+          txRequestId: 'id',
+          isTxRequestFull: true,
+        });
+
+        sandbox.assert.calledOnce(getUserKeyAndSignTssTxSpy);
+        sandbox.assert.calledWithExactly(getUserKeyAndSignTssTxSpy, {
+          walletPassphrase: 'passphrase',
+          txRequestId: 'id',
+        });
+      });
     });
 
     describe('Message Signing', function () {
diff --git a/modules/sdk-core/src/bitgo/wallet/iWallet.ts b/modules/sdk-core/src/bitgo/wallet/iWallet.ts
index 107962047e..2c34c679ac 100644
--- a/modules/sdk-core/src/bitgo/wallet/iWallet.ts
+++ b/modules/sdk-core/src/bitgo/wallet/iWallet.ts
@@ -470,6 +470,11 @@ export interface SignAndSendTxRequestOptions {
   txRequestId: string;
   walletPassphrase: string;
   isTxRequestFull: boolean;
+  /**
+   * Optional WebAuthn proof from the current signer for the request's withdrawal intent;
+   * pass-through only. Sent on the first signing round only, never on the lite submit.
+   */
+  attestation?: AttestationPayload;
 }
 
 export interface SignAndSendMessageTxRequestOptions {
diff --git a/modules/sdk-core/src/bitgo/wallet/wallet.ts b/modules/sdk-core/src/bitgo/wallet/wallet.ts
index 3a37110801..b9e4da44e2 100644
--- a/modules/sdk-core/src/bitgo/wallet/wallet.ts
+++ b/modules/sdk-core/src/bitgo/wallet/wallet.ts
@@ -58,7 +58,7 @@ import { EcdsaMPCv2Utils, EcdsaUtils } from '../utils/tss/ecdsa';
 import EddsaUtils, { EddsaMPCv2Utils } from '../utils/tss/eddsa';
 import { RedpallasMPCv2Utils } from '../utils/tss/redpallas';
 import { getTxRequestApiVersion, validateTxRequestApiVersion } from '../utils/txRequest';
-import { buildParamKeys, BuildParams, ERC7984_INTENT_TX_TYPES } from './BuildParams';
+import { AttestationPayload, buildParamKeys, BuildParams, ERC7984_INTENT_TX_TYPES } from './BuildParams';
 import {
   fetchRootKeychainForSafeChild,
   isSafeChildPublicOnlyKeychain,
@@ -2315,9 +2315,12 @@ export class Wallet implements IWallet {
   async getUserKeyAndSignTssTransaction({
     txRequestId,
     walletPassphrase,
+    attestation,
   }: {
     txRequestId: string;
     walletPassphrase: string;
+    /** Optional WebAuthn proof for the first TSS withdrawal-signing round; pass-through only. */
+    attestation?: AttestationPayload;
   }): Promise<SignedTransaction> {
     if (this._wallet.multisigType !== 'tss') {
       throw new Error('getUserKeyAndSignTssTransaction is only supported for TSS wallets');
@@ -2338,6 +2341,7 @@ export class Wallet implements IWallet {
       walletPassphrase,
       reqId,
       keychain: userKeychain,
+      ...(attestation !== undefined && { attestation }),
     });
   }
 
@@ -5149,9 +5153,12 @@ export class Wallet implements IWallet {
   public async signAndSendTxRequest(params: SignAndSendTxRequestOptions): Promise<SignedTransaction> {
     await this.tssUtils?.deleteSignatureShares(params.txRequestId);
 
+    // Clearing shares above resets the request to its first signing round, so the attestation
+    // rides on round one. It is not sent with the lite submit below: round one consumes its nonce.
     const ret = await this.getUserKeyAndSignTssTransaction({
       walletPassphrase: params.walletPassphrase,
       txRequestId: params.txRequestId,
+      ...(params.attestation !== undefined && { attestation: params.attestation }),
     });
     if (!params.isTxRequestFull) {
       // It is assumed that if its not a full tx request, then it is a lite tx request