diff --git a/.eslintrc.cjs b/.eslintrc.cjs
index d08459e1a..3b8789c48 100644
--- a/.eslintrc.cjs
+++ b/.eslintrc.cjs
@@ -114,6 +114,7 @@ module.exports = {
           'warn',
           { assertFunctionNames: ['expectVisible', 'expectRowVisible'] },
         ],
+        'playwright/no-force-option': 'off',
       },
     },
   ],
diff --git a/app/components/form/NavGuardModal.tsx b/app/components/form/NavGuardModal.tsx
new file mode 100644
index 000000000..5012b4af3
--- /dev/null
+++ b/app/components/form/NavGuardModal.tsx
@@ -0,0 +1,31 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * Copyright Oxide Computer Company
+ */
+import { Modal } from '~/ui/lib/Modal'
+
+const NavGuardModal = ({
+  onAction,
+  onDismiss,
+}: {
+  onAction: () => void
+  onDismiss: () => void
+}) => (
+  <Modal isOpen onDismiss={onDismiss} title="Confirm navigation">
+    <Modal.Section>
+      Are you sure you want to leave this form? Your progress will be lost.
+    </Modal.Section>
+    <Modal.Footer
+      onAction={onAction}
+      onDismiss={onDismiss}
+      cancelText="Keep editing"
+      actionText="Leave form"
+      actionType="danger"
+    />
+  </Modal>
+)
+
+export { NavGuardModal }
diff --git a/app/components/form/SideModalForm.tsx b/app/components/form/SideModalForm.tsx
index e0e02b7cb..07c0d6692 100644
--- a/app/components/form/SideModalForm.tsx
+++ b/app/components/form/SideModalForm.tsx
@@ -5,7 +5,7 @@
  *
  * Copyright Oxide Computer Company
  */
-import { useEffect, useId, type ReactNode } from 'react'
+import { useEffect, useId, useState, type ReactNode } from 'react'
 import type { FieldValues, UseFormReturn } from 'react-hook-form'
 import { NavigationType, useNavigationType } from 'react-router-dom'
 
@@ -14,6 +14,8 @@ import type { ApiError } from '@oxide/api'
 import { Button } from '~/ui/lib/Button'
 import { SideModal } from '~/ui/lib/SideModal'
 
+import { NavGuardModal } from './NavGuardModal'
+
 type CreateFormProps = {
   formType: 'create'
   /** Only needed if you need to override the default button text (`Create ${resourceName}`) */
@@ -89,9 +91,13 @@ export function SideModalForm<TFieldValues extends FieldValues>({
       ? `Update ${resourceName}`
       : submitLabel || title || `Create ${resourceName}`
 
+  const { isDirty } = form.formState
+  const [showNavGuard, setShowNavGuard] = useState(false)
+  const guardedDismiss = () => (isDirty ? setShowNavGuard(true) : onDismiss())
+
   return (
     <SideModal
-      onDismiss={onDismiss}
+      onDismiss={guardedDismiss}
       isOpen
       title={title || `${formType === 'edit' ? 'Edit' : 'Create'} ${resourceName}`}
       animate={useShouldAnimateModal()}
@@ -134,6 +140,9 @@ export function SideModalForm<TFieldValues extends FieldValues>({
           </Button>
         )}
       </SideModal.Footer>
+      {showNavGuard && (
+        <NavGuardModal onDismiss={() => setShowNavGuard(false)} onAction={onDismiss} />
+      )}
     </SideModal>
   )
 }
diff --git a/test/e2e/nav-guard-modal.e2e.ts b/test/e2e/nav-guard-modal.e2e.ts
new file mode 100644
index 000000000..4e27dbe52
--- /dev/null
+++ b/test/e2e/nav-guard-modal.e2e.ts
@@ -0,0 +1,47 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * Copyright Oxide Computer Company
+ */
+
+import { expect, expectVisible, test } from './utils'
+
+test('navigating away from SideModal form triggers nav guard', async ({ page }) => {
+  const floatingIpsPage = '/projects/mock-project/floating-ips'
+  const floatingIpName = 'my-floating-ip'
+  const formModal = page.getByRole('dialog', { name: 'Create floating IP' })
+  const confirmModal = page.getByRole('dialog', { name: 'Confirm navigation' })
+
+  await page.goto(floatingIpsPage)
+  await page.locator('text="New Floating IP"').click()
+
+  await expectVisible(page, [
+    'role=heading[name*="Create floating IP"]',
+    'role=textbox[name="Name"]',
+    'role=textbox[name="Description"]',
+    'role=button[name="Advanced"]',
+    'role=button[name="Create floating IP"]',
+  ])
+
+  await page.fill('input[name=name]', floatingIpName)
+
+  // form is now dirty, so clicking away should trigger the nav guard
+  // force: true allows us to click even though the "Instances" link is inactive
+  await page.getByRole('link', { name: 'Instances' }).click({ force: true })
+  await expect(confirmModal).toBeVisible()
+
+  // go back to the form
+  await page.getByRole('button', { name: 'Keep editing' }).click()
+  await expect(confirmModal).toBeHidden()
+  await expect(formModal).toBeVisible()
+
+  // now try to navigate away again; verify that clicking the Escape key also triggers it
+  await page.keyboard.press('Escape')
+  await expect(confirmModal).toBeVisible()
+  await page.getByRole('button', { name: 'Leave form' }).click()
+  await expect(confirmModal).toBeHidden()
+  await expect(formModal).toBeHidden()
+  await expect(page).toHaveURL(floatingIpsPage)
+})