diff --git a/frontend/src/components/Dashboard/NetworkSelector.css b/frontend/src/components/Dashboard/NetworkSelector.css
index 7706587..3163bb0 100644
--- a/frontend/src/components/Dashboard/NetworkSelector.css
+++ b/frontend/src/components/Dashboard/NetworkSelector.css
@@ -27,3 +27,70 @@
   font-size: 0.8rem;
   line-height: 1.4;
 }
+
+/* ---- Confirmation dialog ---- */
+.network-selector__confirm-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.5);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+}
+
+.network-selector__confirm-dialog {
+  background: var(--color-surface, #fff);
+  border-radius: var(--radius, 8px);
+  padding: 24px;
+  max-width: 400px;
+  width: 90%;
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.24);
+}
+
+.network-selector__confirm-title {
+  margin: 0 0 12px;
+  font-size: 1rem;
+  font-weight: 600;
+  color: var(--color-text);
+}
+
+.network-selector__confirm-body {
+  margin: 0 0 20px;
+  font-size: 0.9rem;
+  color: var(--color-text-muted, var(--color-text));
+  line-height: 1.5;
+}
+
+.network-selector__confirm-actions {
+  display: flex;
+  gap: 10px;
+  justify-content: flex-end;
+}
+
+.network-selector__btn {
+  padding: 8px 16px;
+  border: none;
+  border-radius: var(--radius, 6px);
+  font-size: 0.875rem;
+  font-weight: 500;
+  cursor: pointer;
+}
+
+.network-selector__btn--danger {
+  background: var(--color-danger, #e53e3e);
+  color: #fff;
+}
+
+.network-selector__btn--danger:hover {
+  opacity: 0.9;
+}
+
+.network-selector__btn--secondary {
+  background: var(--color-input-border, #ccc);
+  color: var(--color-text);
+}
+
+.network-selector__btn--secondary:hover {
+  opacity: 0.85;
+}
diff --git a/frontend/src/components/Dashboard/NetworkSelector.test.tsx b/frontend/src/components/Dashboard/NetworkSelector.test.tsx
new file mode 100644
index 0000000..4f2b457
--- /dev/null
+++ b/frontend/src/components/Dashboard/NetworkSelector.test.tsx
@@ -0,0 +1,131 @@
+/**
+ * Tests for NetworkSelector confirmation dialog (Issue #1).
+ *
+ * Verifies that:
+ *  - switching networks without dirty form state switches immediately.
+ *  - switching networks with dirty form state shows a confirmation prompt.
+ *  - confirming the switch actually changes the network.
+ *  - cancelling the switch leaves the network unchanged.
+ */
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import "@testing-library/jest-dom";
+import { render, screen, fireEvent } from "@testing-library/react";
+import NetworkSelector from "./NetworkSelector";
+
+// ---- Mock useNetwork -------------------------------------------------------
+const mockSetNetwork = vi.fn();
+let currentNetwork: "testnet" | "mainnet" = "testnet";
+
+vi.mock("../../hooks/useNetwork", () => ({
+  useNetwork: () => ({
+    network: currentNetwork,
+    setNetwork: mockSetNetwork,
+    isMainnet: currentNetwork === "mainnet",
+    rpcUrl: "https://soroban-testnet.stellar.org",
+    hasNetworkMismatch: false,
+    walletPassphrase: null,
+    walletNetwork: null,
+    isCheckingWallet: false,
+  }),
+}));
+
+// ---- Helpers ---------------------------------------------------------------
+
+function registerDirtyForm(key = "test-form") {
+  if (!window.__networkSelectorDirtyForms) {
+    window.__networkSelectorDirtyForms = new Set();
+  }
+  window.__networkSelectorDirtyForms.add(key);
+}
+
+function clearDirtyForms() {
+  window.__networkSelectorDirtyForms?.clear();
+}
+
+// ---- Tests -----------------------------------------------------------------
+
+describe("NetworkSelector", () => {
+  beforeEach(() => {
+    currentNetwork = "testnet";
+    mockSetNetwork.mockClear();
+    clearDirtyForms();
+  });
+
+  afterEach(() => {
+    clearDirtyForms();
+  });
+
+  it("renders the network selector with the current network selected", () => {
+    render(<NetworkSelector />);
+    const select = screen.getByRole("combobox", { name: /select network/i });
+    expect(select).toHaveValue("testnet");
+  });
+
+  it("switches network immediately when no dirty forms are registered", () => {
+    render(<NetworkSelector />);
+    const select = screen.getByRole("combobox", { name: /select network/i });
+    fireEvent.change(select, { target: { value: "mainnet" } });
+    // Dialog should NOT appear
+    expect(screen.queryByRole("dialog")).not.toBeInTheDocument();
+    // Network should switch directly
+    expect(mockSetNetwork).toHaveBeenCalledWith("mainnet");
+  });
+
+  it("shows the confirmation dialog when switching with dirty form state", () => {
+    registerDirtyForm("settlement-proposal");
+    render(<NetworkSelector />);
+    const select = screen.getByRole("combobox", { name: /select network/i });
+    fireEvent.change(select, { target: { value: "mainnet" } });
+
+    // Dialog must be visible
+    expect(screen.getByRole("dialog")).toBeInTheDocument();
+    expect(screen.getByText(/unsaved changes/i)).toBeInTheDocument();
+    // The dialog body mentions the pending network name
+    expect(screen.getByText(/switching to/i)).toBeInTheDocument();
+
+    // Network must NOT have switched yet
+    expect(mockSetNetwork).not.toHaveBeenCalled();
+  });
+
+  it("confirms the switch when the user clicks 'Switch network'", () => {
+    registerDirtyForm("settlement-proposal");
+    render(<NetworkSelector />);
+
+    fireEvent.change(screen.getByRole("combobox"), {
+      target: { value: "mainnet" },
+    });
+
+    // Confirm
+    fireEvent.click(screen.getByTestId("ns-confirm-switch"));
+
+    expect(mockSetNetwork).toHaveBeenCalledWith("mainnet");
+    expect(screen.queryByRole("dialog")).not.toBeInTheDocument();
+  });
+
+  it("cancels the switch when the user clicks 'Keep editing'", () => {
+    registerDirtyForm("settlement-proposal");
+    render(<NetworkSelector />);
+
+    fireEvent.change(screen.getByRole("combobox"), {
+      target: { value: "mainnet" },
+    });
+
+    // Cancel
+    fireEvent.click(screen.getByTestId("ns-cancel-switch"));
+
+    expect(mockSetNetwork).not.toHaveBeenCalled();
+    expect(screen.queryByRole("dialog")).not.toBeInTheDocument();
+  });
+
+  it("shows the mainnet warning when on mainnet", () => {
+    currentNetwork = "mainnet";
+    render(<NetworkSelector />);
+    expect(screen.getByRole("alert")).toHaveTextContent(/mainnet/i);
+  });
+
+  it("does not show the mainnet warning when on testnet", () => {
+    currentNetwork = "testnet";
+    render(<NetworkSelector />);
+    expect(screen.queryByRole("alert")).not.toBeInTheDocument();
+  });
+});
diff --git a/frontend/src/components/Dashboard/NetworkSelector.tsx b/frontend/src/components/Dashboard/NetworkSelector.tsx
index 236578c..79f830d 100644
--- a/frontend/src/components/Dashboard/NetworkSelector.tsx
+++ b/frontend/src/components/Dashboard/NetworkSelector.tsx
@@ -1,26 +1,115 @@
+import { useState, useCallback } from "react";
 import { useNetwork } from "../../hooks/useNetwork";
 import "./NetworkSelector.css";
 
+/**
+ * Context key used by any form in the dashboard to register itself as "dirty".
+ * Forms call `window.__networkSelectorDirtyForms.add(key)` on change and
+ * `window.__networkSelectorDirtyForms.delete(key)` on submit/reset.
+ *
+ * NetworkSelector reads this set before switching networks so it can prompt
+ * the user when unsaved state would be lost.
+ */
+declare global {
+  interface Window {
+    __networkSelectorDirtyForms?: Set<string>;
+  }
+}
+
+/** Returns true when at least one form has registered unsaved state. */
+function hasDirtyForms(): boolean {
+  return (window.__networkSelectorDirtyForms?.size ?? 0) > 0;
+}
+
 export default function NetworkSelector() {
   const { network, setNetwork, isMainnet } = useNetwork();
+  const [pendingNetwork, setPendingNetwork] = useState<
+    "testnet" | "mainnet" | null
+  >(null);
+
+  const handleChange = useCallback(
+    (e: React.ChangeEvent<HTMLSelectElement>) => {
+      const next = e.target.value as "testnet" | "mainnet";
+      if (next === network) return;
+
+      if (hasDirtyForms()) {
+        // Park the requested switch and ask for confirmation.
+        setPendingNetwork(next);
+      } else {
+        setNetwork(next);
+      }
+    },
+    [network, setNetwork],
+  );
+
+  const confirmSwitch = useCallback(() => {
+    if (pendingNetwork) {
+      setNetwork(pendingNetwork);
+    }
+    setPendingNetwork(null);
+  }, [pendingNetwork, setNetwork]);
+
+  const cancelSwitch = useCallback(() => {
+    setPendingNetwork(null);
+  }, []);
 
   return (
     <div className="network-selector">
       <select
         className="network-selector__select"
         value={network}
-        onChange={(e) => setNetwork(e.target.value as "testnet" | "mainnet")}
+        onChange={handleChange}
         aria-label="Select network"
       >
         <option value="testnet">Testnet</option>
         <option value="mainnet">Mainnet</option>
       </select>
+
       {isMainnet && (
         <div className="network-selector__warning" role="alert">
           ⚠️ You are connected to <strong>Mainnet</strong>. Transactions are
           irreversible and use real funds.
         </div>
       )}
+
+      {pendingNetwork !== null && (
+        <div
+          className="network-selector__confirm-overlay"
+          role="dialog"
+          aria-modal="true"
+          aria-labelledby="ns-confirm-title"
+          aria-describedby="ns-confirm-desc"
+        >
+          <div className="network-selector__confirm-dialog">
+            <h3 id="ns-confirm-title" className="network-selector__confirm-title">
+              Unsaved changes
+            </h3>
+            <p id="ns-confirm-desc" className="network-selector__confirm-body">
+              You have unsaved form data. Switching to{" "}
+              <strong>{pendingNetwork}</strong> will discard those changes. Do
+              you want to continue?
+            </p>
+            <div className="network-selector__confirm-actions">
+              <button
+                type="button"
+                className="network-selector__btn network-selector__btn--danger"
+                onClick={confirmSwitch}
+                data-testid="ns-confirm-switch"
+              >
+                Switch network
+              </button>
+              <button
+                type="button"
+                className="network-selector__btn network-selector__btn--secondary"
+                onClick={cancelSwitch}
+                data-testid="ns-cancel-switch"
+              >
+                Keep editing
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
     </div>
   );
 }