diff --git a/web/account/siwe.react.js b/web/account/siwe.react.js
--- a/web/account/siwe.react.js
+++ b/web/account/siwe.react.js
@@ -9,6 +9,7 @@
   RainbowKitProvider,
   useConnectModal,
 } from '@rainbow-me/rainbowkit';
+import invariant from 'invariant';
 import _merge from 'lodash/fp/merge';
 import * as React from 'react';
 import { FaEthereum } from 'react-icons/fa';
@@ -16,6 +17,7 @@
   chain,
   configureChains,
   createClient,
+  useAccount,
   useSigner,
   WagmiConfig,
 } from 'wagmi';
@@ -31,7 +33,11 @@
   useDispatchActionPromise,
   useServerCall,
 } from 'lib/utils/action-utils';
-import { siweMessageSigningExplanationStatements } from 'lib/utils/siwe-utils.js';
+import {
+  createSIWEMessage,
+  siweMessageSigningExplanationStatements,
+  siweStatementWithoutPublicKey,
+} from 'lib/utils/siwe-utils.js';
 
 import Button from '../components/button.react';
 import LoadingIndicator from '../loading-indicator.react';
@@ -63,6 +69,7 @@
 );
 function SIWE(): React.Node {
   const { openConnectModal } = useConnectModal();
+  const { address } = useAccount();
   const { data: signer } = useSigner();
   const dispatchActionPromise = useDispatchActionPromise();
   const getSIWENonceCall = useServerCall(getSIWENonce);
@@ -91,6 +98,16 @@
     [],
   );
 
+  const onSignInButtonClick = React.useCallback(async () => {
+    invariant(siweNonce, 'nonce must be present during SIWE attempt');
+    const message = createSIWEMessage(
+      address,
+      siweStatementWithoutPublicKey,
+      siweNonce,
+    );
+    await signer.signMessage(message);
+  }, [address, signer, siweNonce]);
+
   let siweLoginForm;
   if (signer && !siweNonce) {
     siweLoginForm = (
@@ -109,7 +126,7 @@
         </div>
         <p>{siweMessageSigningExplanationStatements[0]}</p>
         <p>{siweMessageSigningExplanationStatements[1]}</p>
-        <Button variant="filled" type="submit" onClick={undefined}>
+        <Button variant="filled" onClick={onSignInButtonClick}>
           Sign in
         </Button>
       </div>