diff --git a/apps/web/components/watchlists/WatchlistCreationModal.spec.tsx b/apps/web/components/watchlists/WatchlistCreationModal.spec.tsx
new file mode 100644
index 0000000..5471199
--- /dev/null
+++ b/apps/web/components/watchlists/WatchlistCreationModal.spec.tsx
@@ -0,0 +1,53 @@
+import { fireEvent, render, screen, waitFor } from '@testing-library/react';
+import { WatchlistCreationModal } from './WatchlistCreationModal';
+
+describe('WatchlistCreationModal', () => {
+  it('requires a name and at least one target', () => {
+    const onCreate = jest.fn();
+    render(<WatchlistCreationModal onClose={jest.fn()} onCreate={onCreate} />);
+
+    fireEvent.click(screen.getByRole('button', { name: /create watchlist/i }));
+
+    expect(screen.getByText('Enter a name for this watchlist.')).toBeTruthy();
+    expect(screen.getByText('Add a wallet address, contract address, or both.')).toBeTruthy();
+    expect(onCreate).not.toHaveBeenCalled();
+  });
+
+  it('submits trimmed values and closes after creation succeeds', async () => {
+    const onCreate = jest.fn().mockResolvedValue(undefined);
+    const onClose = jest.fn();
+    render(<WatchlistCreationModal onClose={onClose} onCreate={onCreate} />);
+
+    fireEvent.change(screen.getByLabelText('Watchlist name'), {
+      target: { value: '  Treasury  ' },
+    });
+    fireEvent.change(screen.getByLabelText(/wallet address/i), {
+      target: { value: '  GABC123  ' },
+    });
+    fireEvent.click(screen.getByRole('button', { name: /create watchlist/i }));
+
+    await waitFor(() =>
+      expect(onCreate).toHaveBeenCalledWith({
+        label: 'Treasury',
+        walletAddress: 'GABC123',
+        contractAddress: undefined,
+      }),
+    );
+    expect(onClose).toHaveBeenCalledTimes(1);
+  });
+
+  it('keeps the dialog open and reports a submission error', async () => {
+    const onCreate = jest.fn().mockRejectedValue(new Error('Address could not be saved.'));
+    const onClose = jest.fn();
+    render(<WatchlistCreationModal onClose={onClose} onCreate={onCreate} />);
+
+    fireEvent.change(screen.getByLabelText('Watchlist name'), { target: { value: 'Treasury' } });
+    fireEvent.change(screen.getByLabelText(/contract address/i), {
+      target: { value: 'contract-1' },
+    });
+    fireEvent.click(screen.getByRole('button', { name: /create watchlist/i }));
+
+    expect((await screen.findByRole('alert')).textContent).toContain('Address could not be saved.');
+    expect(onClose).not.toHaveBeenCalled();
+  });
+});
diff --git a/apps/web/components/watchlists/WatchlistCreationModal.tsx b/apps/web/components/watchlists/WatchlistCreationModal.tsx
new file mode 100644
index 0000000..1ebd3f4
--- /dev/null
+++ b/apps/web/components/watchlists/WatchlistCreationModal.tsx
@@ -0,0 +1,190 @@
+'use client';
+
+import { useState } from 'react';
+import './watchlists.css';
+
+export interface WatchlistCreationPayload {
+  label: string;
+  walletAddress?: string;
+  contractAddress?: string;
+}
+
+interface WatchlistCreationModalProps {
+  onClose: () => void;
+  onCreate: (payload: WatchlistCreationPayload) => Promise<void> | void;
+}
+
+type FormErrors = Partial<Record<keyof WatchlistCreationPayload | 'targets', string>>;
+
+const MAX_LABEL_LENGTH = 100;
+const MAX_ADDRESS_LENGTH = 256;
+
+export function WatchlistCreationModal({ onClose, onCreate }: WatchlistCreationModalProps) {
+  const [label, setLabel] = useState('');
+  const [walletAddress, setWalletAddress] = useState('');
+  const [contractAddress, setContractAddress] = useState('');
+  const [errors, setErrors] = useState<FormErrors>({});
+  const [submitError, setSubmitError] = useState('');
+  const [isSubmitting, setIsSubmitting] = useState(false);
+
+  const validate = (): FormErrors => {
+    const nextErrors: FormErrors = {};
+    const trimmedLabel = label.trim();
+    const trimmedWallet = walletAddress.trim();
+    const trimmedContract = contractAddress.trim();
+
+    if (!trimmedLabel) nextErrors.label = 'Enter a name for this watchlist.';
+    else if (trimmedLabel.length > MAX_LABEL_LENGTH) {
+      nextErrors.label = `Name must be ${MAX_LABEL_LENGTH} characters or fewer.`;
+    }
+
+    if (!trimmedWallet && !trimmedContract) {
+      nextErrors.targets = 'Add a wallet address, contract address, or both.';
+    }
+    if (trimmedWallet.length > MAX_ADDRESS_LENGTH) {
+      nextErrors.walletAddress = 'Wallet address is too long.';
+    }
+    if (trimmedContract.length > MAX_ADDRESS_LENGTH) {
+      nextErrors.contractAddress = 'Contract address is too long.';
+    }
+    if (trimmedWallet && trimmedContract && trimmedWallet === trimmedContract) {
+      nextErrors.targets = 'Wallet and contract addresses must be different.';
+    }
+
+    return nextErrors;
+  };
+
+  const handleSubmit = async (event: React.FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+    setSubmitError('');
+
+    const nextErrors = validate();
+    setErrors(nextErrors);
+    if (Object.keys(nextErrors).length > 0) return;
+
+    setIsSubmitting(true);
+    try {
+      await onCreate({
+        label: label.trim(),
+        walletAddress: walletAddress.trim() || undefined,
+        contractAddress: contractAddress.trim() || undefined,
+      });
+      onClose();
+    } catch (error) {
+      setSubmitError(error instanceof Error ? error.message : 'Unable to create watchlist.');
+    } finally {
+      setIsSubmitting(false);
+    }
+  };
+
+  return (
+    <div className="watchlist-modal-backdrop" role="presentation" onMouseDown={onClose}>
+      <section
+        className="watchlist-modal"
+        role="dialog"
+        aria-modal="true"
+        aria-labelledby="watchlist-modal-title"
+        onMouseDown={event => event.stopPropagation()}
+      >
+        <header className="watchlist-modal-header">
+          <div>
+            <p className="watchlist-modal-eyebrow">Monitoring</p>
+            <h2 id="watchlist-modal-title">Create watchlist</h2>
+            <p>Choose the addresses Sentinel should keep an eye on.</p>
+          </div>
+          <button
+            type="button"
+            className="watchlist-modal-close"
+            onClick={onClose}
+            aria-label="Close"
+          >
+            ×
+          </button>
+        </header>
+
+        <form onSubmit={handleSubmit} noValidate>
+          <div className="watchlist-field">
+            <label htmlFor="watchlist-label">Watchlist name</label>
+            <input
+              id="watchlist-label"
+              value={label}
+              onChange={event => setLabel(event.target.value)}
+              aria-invalid={Boolean(errors.label)}
+              aria-describedby={errors.label ? 'watchlist-label-error' : undefined}
+              placeholder="e.g. Treasury movement"
+              maxLength={MAX_LABEL_LENGTH}
+              disabled={isSubmitting}
+            />
+            {errors.label && (
+              <p id="watchlist-label-error" className="watchlist-error">
+                {errors.label}
+              </p>
+            )}
+          </div>
+
+          <div className="watchlist-field">
+            <label htmlFor="watchlist-wallet">
+              Wallet address <span>(optional)</span>
+            </label>
+            <input
+              id="watchlist-wallet"
+              value={walletAddress}
+              onChange={event => setWalletAddress(event.target.value)}
+              aria-invalid={Boolean(errors.walletAddress || errors.targets)}
+              aria-describedby={errors.walletAddress ? 'watchlist-wallet-error' : undefined}
+              placeholder="Paste a wallet address"
+              maxLength={MAX_ADDRESS_LENGTH}
+              disabled={isSubmitting}
+            />
+            {errors.walletAddress && (
+              <p id="watchlist-wallet-error" className="watchlist-error">
+                {errors.walletAddress}
+              </p>
+            )}
+          </div>
+
+          <div className="watchlist-field">
+            <label htmlFor="watchlist-contract">
+              Contract address <span>(optional)</span>
+            </label>
+            <input
+              id="watchlist-contract"
+              value={contractAddress}
+              onChange={event => setContractAddress(event.target.value)}
+              aria-invalid={Boolean(errors.contractAddress || errors.targets)}
+              aria-describedby={errors.contractAddress ? 'watchlist-contract-error' : undefined}
+              placeholder="Paste a contract address"
+              maxLength={MAX_ADDRESS_LENGTH}
+              disabled={isSubmitting}
+            />
+            {errors.contractAddress && (
+              <p id="watchlist-contract-error" className="watchlist-error">
+                {errors.contractAddress}
+              </p>
+            )}
+          </div>
+
+          {errors.targets && (
+            <p className="watchlist-error" role="alert">
+              {errors.targets}
+            </p>
+          )}
+          {submitError && (
+            <p className="watchlist-error" role="alert">
+              {submitError}
+            </p>
+          )}
+
+          <footer className="watchlist-modal-actions">
+            <button type="button" onClick={onClose} disabled={isSubmitting}>
+              Cancel
+            </button>
+            <button type="submit" disabled={isSubmitting}>
+              {isSubmitting ? 'Creating...' : 'Create watchlist'}
+            </button>
+          </footer>
+        </form>
+      </section>
+    </div>
+  );
+}
diff --git a/apps/web/components/watchlists/watchlists.css b/apps/web/components/watchlists/watchlists.css
new file mode 100644
index 0000000..4700c48
--- /dev/null
+++ b/apps/web/components/watchlists/watchlists.css
@@ -0,0 +1,151 @@
+.watchlist-modal-backdrop {
+  position: fixed;
+  inset: 0;
+  z-index: 50;
+  display: grid;
+  place-items: center;
+  padding: 1rem;
+  background: rgb(8 15 29 / 72%);
+}
+
+.watchlist-modal {
+  width: min(100%, 32rem);
+  max-height: calc(100dvh - 2rem);
+  overflow-y: auto;
+  border: 1px solid #c9d5e6;
+  border-radius: 0.75rem;
+  background: #f8fafc;
+  color: #142238;
+  box-shadow: 0 1.5rem 4rem rgb(5 15 35 / 28%);
+}
+
+.watchlist-modal-header {
+  display: flex;
+  justify-content: space-between;
+  gap: 1rem;
+  padding: 1.5rem 1.5rem 1rem;
+  border-bottom: 1px solid #dbe4ef;
+}
+
+.watchlist-modal-eyebrow {
+  margin: 0 0 0.35rem;
+  color: #147d75;
+  font-size: 0.7rem;
+  font-weight: 700;
+  letter-spacing: 0.08em;
+  text-transform: uppercase;
+}
+
+.watchlist-modal h2 {
+  margin: 0;
+  font-size: 1.45rem;
+  line-height: 1.2;
+}
+
+.watchlist-modal-header p:last-child {
+  margin: 0.45rem 0 0;
+  color: #52647c;
+  font-size: 0.9rem;
+}
+
+.watchlist-modal-close {
+  align-self: flex-start;
+  border: 0;
+  background: transparent;
+  color: #52647c;
+  cursor: pointer;
+  font-size: 1.5rem;
+  line-height: 1;
+}
+
+.watchlist-modal form {
+  padding: 1.25rem 1.5rem 1.5rem;
+}
+
+.watchlist-field {
+  display: grid;
+  gap: 0.4rem;
+  margin-bottom: 1rem;
+}
+
+.watchlist-field label {
+  color: #263b56;
+  font-size: 0.85rem;
+  font-weight: 700;
+}
+
+.watchlist-field label span {
+  color: #718198;
+  font-weight: 400;
+}
+
+.watchlist-field input {
+  width: 100%;
+  box-sizing: border-box;
+  border: 1px solid #b8c7da;
+  border-radius: 0.4rem;
+  padding: 0.7rem 0.75rem;
+  background: #fff;
+  color: #142238;
+  font: inherit;
+}
+
+.watchlist-field input:focus {
+  outline: 3px solid rgb(20 125 117 / 18%);
+  border-color: #147d75;
+}
+
+.watchlist-field input[aria-invalid='true'] {
+  border-color: #c24146;
+}
+
+.watchlist-error {
+  margin: 0.35rem 0 0;
+  color: #a52d37;
+  font-size: 0.8rem;
+}
+
+.watchlist-modal-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 0.75rem;
+  margin-top: 1.5rem;
+}
+
+.watchlist-modal-actions button {
+  border: 1px solid #b8c7da;
+  border-radius: 0.4rem;
+  padding: 0.65rem 1rem;
+  cursor: pointer;
+  font: inherit;
+  font-weight: 700;
+}
+
+.watchlist-modal-actions button:first-child {
+  background: #fff;
+  color: #314661;
+}
+
+.watchlist-modal-actions button:last-child {
+  border-color: #147d75;
+  background: #147d75;
+  color: #fff;
+}
+
+.watchlist-modal-actions button:disabled {
+  cursor: wait;
+  opacity: 0.6;
+}
+
+@media (max-width: 32rem) {
+  .watchlist-modal-header,
+  .watchlist-modal form {
+    padding-left: 1rem;
+    padding-right: 1rem;
+  }
+
+  .watchlist-modal-actions {
+    display: grid;
+    grid-template-columns: 1fr 1fr;
+  }
+}