diff --git a/frontend/src/index.jsx b/frontend/src/index.jsx
index 539727c..542a31e 100644
--- a/frontend/src/index.jsx
+++ b/frontend/src/index.jsx
@@ -40,7 +40,9 @@ import usePasskeys from './settings/usePasskeys';
 import {
   isWebAuthnAvailable,
   preparePublicKeyRequestOptions,
+  preparePublicKeyCreationOptions,
   serializeAuthenticationCredential,
+  serializeRegistrationCredential,
 } from './utils/webauthn';
 
 const ASSET_PRESIGN_TTL_MS = 240 * 1000; // backend issues 5 min tokens; refresh slightly early
@@ -5699,6 +5701,8 @@ const LoginRoute = () => {
   const [selectingTenantId, setSelectingTenantId] = useState(null);
   const passkeySupported = isWebAuthnAvailable();
   const [passkeyLoading, setPasskeyLoading] = useState(false);
+  const signupSupported = passkeySupported;
+  const [signupLoading, setSignupLoading] = useState(false);
 
   const setStatusMessage = useCallback((message, variant = 'info') => {
     setStatus(message ? { message, variant } : null);
@@ -5775,13 +5779,8 @@ const LoginRoute = () => {
       appDispatch({ type: 'LOGIN_REQUEST' });
       try {
         const { data: startData } = await api.post('/auth/passkeys/login/start', { username });
-        const challengeId = startData?.challengeId || startData?.challenge_id;
-        const publicKeyOptions =
-          startData?.publicKey
-          || startData?.public_key
-          || startData?.publicKeyCredentialRequestOptions
-          || startData?.challenge?.publicKey
-          || startData?.challenge?.public_key;
+        const challengeId = startData.challengeId;
+        const publicKeyOptions = startData.publicKey;
 
         if (!challengeId || !publicKeyOptions) {
           throw new Error('Invalid passkey challenge response.');
@@ -5828,7 +5827,7 @@ const LoginRoute = () => {
         if (error?.name === 'NotAllowedError') {
           setStatusMessage('Passkey login cancelled.', 'info');
         } else if (error?.response?.status === 404) {
-          setStatusMessage('No passkeys found for this user. Sign in with your password to add one.', 'error');
+          setStatusMessage('No passkey registered for this username. Create an account first.', 'error');
           appDispatch({ type: 'LOGIN_FAILURE', error: 'passkey not registered' });
         } else if (error?.response?.status === 400 && error?.response?.data?.error) {
           setStatusMessage(error.response.data.error, 'error');
@@ -5845,6 +5844,85 @@ const LoginRoute = () => {
     [appDispatch, notifyLoginError, passkeySupported, setStatusMessage],
   );
 
+  const handleSignup = useCallback(
+    async (rawUsername) => {
+      const username = (rawUsername || '').trim();
+      if (!username) {
+        setStatusMessage('Choose a username to create your account.', 'error');
+        return;
+      }
+      if (!passkeySupported) {
+        setStatusMessage('Passkeys are not supported in this browser.', 'error');
+        return;
+      }
+
+      setSignupLoading(true);
+      try {
+        const { data: startData } = await api.post('/auth/signup/start', { username });
+        const signupToken = startData.signup_token;
+        const challengePayload = startData.challenge;
+        const challengeId = challengePayload?.challengeId;
+        const publicKeyOptions = challengePayload?.publicKey;
+
+        if (!signupToken || !challengeId || !publicKeyOptions) {
+          throw new Error('Invalid signup challenge response.');
+        }
+
+        const publicKey = preparePublicKeyCreationOptions({ publicKey: publicKeyOptions });
+        setStatusMessage('Confirm the passkey prompt to finish creating your account.', 'info');
+        const credential = await navigator.credentials.create({ publicKey });
+
+        if (!credential) {
+          setStatusMessage('Signup cancelled.', 'info');
+          return;
+        }
+
+        const serialized = serializeRegistrationCredential(credential);
+        const finishPayload = {
+          signup_token: signupToken,
+          credential: serialized,
+        };
+
+        const { data: finishData } = await api.post('/auth/signup/finish', finishPayload);
+
+        if (finishData?.access_token && Array.isArray(finishData?.tenants)) {
+          appDispatch({
+            type: 'TENANT_SELECTION_REQUIRED',
+            selectionToken: finishData.access_token,
+            tenants: finishData.tenants,
+          });
+          setStatusMessage('Select a tenant to continue.', 'info');
+          return;
+        }
+
+        if (!finishData?.access_token) {
+          throw new Error('Invalid signup response.');
+        }
+
+        appDispatch({
+          type: 'LOGIN_SUCCESS',
+          token: finishData.access_token,
+          tenant: finishData.tenant || null,
+        });
+        setStatusMessage('Account created. Welcome!', 'success');
+      } catch (error) {
+        if (error?.name === 'NotAllowedError') {
+          setStatusMessage('Signup cancelled.', 'info');
+        } else if (error?.response?.status === 409) {
+          setStatusMessage('This passkey is already registered. Try signing in instead.', 'error');
+        } else if (error?.response?.data?.error) {
+          setStatusMessage(error.response.data.error, 'error');
+        } else {
+          const message = error?.message || 'Failed to create account.';
+          setStatusMessage(message, 'error');
+        }
+      } finally {
+        setSignupLoading(false);
+      }
+    },
+    [appDispatch, passkeySupported, setStatusMessage],
+  );
+
   const redirectTarget = useMemo(() => {
     const target = location.state?.from;
     if (typeof target === 'string' && target.startsWith('/')) {
@@ -5868,6 +5946,9 @@ const LoginRoute = () => {
         onPasskeyLogin={handlePasskeyLogin}
         passkeySupported={passkeySupported}
         passkeyLoading={passkeyLoading}
+        onSignup={handleSignup}
+        signupSupported={signupSupported}
+        signupLoading={signupLoading}
       />
     </div>
   );
diff --git a/frontend/src/login/LoginView.jsx b/frontend/src/login/LoginView.jsx
index c769a6a..8b05db9 100644
--- a/frontend/src/login/LoginView.jsx
+++ b/frontend/src/login/LoginView.jsx
@@ -12,8 +12,11 @@ const LoginView = ({
   onCancelSelection,
   selectingTenantId,
   onPasskeyLogin,
+  onSignup,
   passkeySupported = false,
   passkeyLoading = false,
+  signupSupported = false,
+  signupLoading = false,
 }) => {
   const hasTenantSelection = Boolean(tenantSelection?.tenants?.length);
   const [username, setUsername] = useState('');
@@ -25,6 +28,21 @@ const LoginView = ({
     onPasskeyLogin(username);
   };
 
+  const handleSignupClick = () => {
+    if (!onSignup) {
+      return;
+    }
+    onSignup(username);
+  };
+
+  const handleSubmit = (event) => {
+    event.preventDefault();
+    if (!passkeySupported || passkeyLoading || !username.trim()) {
+      return;
+    }
+    handlePasskeyClick();
+  };
+
   return (
     <div className="login-screen">
       <div className="login-card">
@@ -60,29 +78,40 @@ const LoginView = ({
           </div>
         ) : (
           <>
-            <p>Use your registered passkey to sign in.</p>
-            <label htmlFor="username">Username</label>
-            <input
-              id="username"
-              name="username"
-              value={username}
-              onChange={(event) => setUsername(event.target.value)}
-              placeholder="Username"
-              autoComplete="username"
-              required
-            />
-            {passkeySupported ? (
+            <p>Use your registered passkey to sign in or create a new account.</p>
+            <form className="login-card__fields" onSubmit={handleSubmit}>
+              <label htmlFor="username">Username</label>
+              <input
+                id="username"
+                name="username"
+                value={username}
+                onChange={(event) => setUsername(event.target.value)}
+                placeholder="Username"
+                autoComplete="username"
+                required
+              />
+              {passkeySupported ? (
+                <button
+                  type="submit"
+                  className="login-card__passkey-button"
+                  disabled={passkeyLoading || !username.trim()}
+                >
+                  {passkeyLoading ? 'Signing in…' : 'Sign in with passkey'}
+                </button>
+              ) : (
+                <p className="settings-empty">Passkeys are not supported in this browser.</p>
+              )}
+            </form>
+            {signupSupported ? (
               <button
                 type="button"
-                className="secondary login-card__passkey-button"
-                onClick={handlePasskeyClick}
-                disabled={passkeyLoading || !username.trim()}
+                className="login-card__signup-button"
+                onClick={handleSignupClick}
+                disabled={signupLoading || !username.trim()}
               >
-                {passkeyLoading ? 'Signing in…' : 'Sign in with passkey'}
+                {signupLoading ? 'Creating account…' : 'Create account with passkey'}
               </button>
-            ) : (
-              <p className="settings-empty">Passkeys are not supported in this browser.</p>
-            )}
+            ) : null}
           </>
         )}
         <StatusBanner status={status} />
diff --git a/frontend/src/styles.css b/frontend/src/styles.css
index 436ec67..3d6f8ff 100644
--- a/frontend/src/styles.css
+++ b/frontend/src/styles.css
@@ -2896,6 +2896,27 @@ form.inline {
   color: var(--muted);
 }
 
+.login-card__fields {
+  display: flex;
+  flex-direction: column;
+  gap: 0.75rem;
+  width: 100%;
+}
+
+.login-card__passkey-button {
+  margin-top: 1rem;
+  width: 100%;
+  display: inline-flex;
+  justify-content: center;
+}
+
+.login-card__signup-button {
+  margin-top: 0.75rem;
+  width: 100%;
+  display: inline-flex;
+  justify-content: center;
+}
+
 .login-card .status-banner {
   margin-bottom: 0;
 }