diff --git a/packages/@headlessui-react/src/components/combobox/combobox.test.tsx b/packages/@headlessui-react/src/components/combobox/combobox.test.tsx
index a8bcbfa0e6..62b56953f7 100644
--- a/packages/@headlessui-react/src/components/combobox/combobox.test.tsx
+++ b/packages/@headlessui-react/src/components/combobox/combobox.test.tsx
@@ -4400,6 +4400,10 @@ describe('Keyboard interactions', () => {
 
           let options: ReturnType<typeof getComboboxOptions>
 
+          options = getComboboxOptions()
+          expect(options[0]).toHaveTextContent('person a')
+          assertActiveComboboxOption(options[0])
+
           await press(Keys.ArrowDown)
 
           // Person B should be active
@@ -5646,6 +5650,50 @@ describe('Multi-select', () => {
       assertComboboxOption(options[2], { selected: true })
     })
   )
+
+  it(
+    'should reset the active option, if the active option gets unmounted',
+    suppressConsoleLogs(async () => {
+      let users = ['alice', 'bob', 'charlie']
+      function Example() {
+        let [value, setValue] = useState<string[]>([])
+
+        return (
+          <Combobox value={value} onChange={(value) => setValue(value)} multiple>
+            <Combobox.Input onChange={() => {}} />
+            <Combobox.Button>Trigger</Combobox.Button>
+            <Combobox.Options>
+              {users
+                .filter((user) => !value.includes(user))
+                .map((user) => (
+                  <Combobox.Option key={user} value={user}>
+                    {user}
+                  </Combobox.Option>
+                ))}
+            </Combobox.Options>
+          </Combobox>
+        )
+      }
+
+      render(<Example />)
+
+      // Open combobox
+      await click(getComboboxButton())
+      assertCombobox({ state: ComboboxState.Visible })
+
+      let options = getComboboxOptions()
+
+      // Go to the next option
+      await press(Keys.ArrowDown)
+      assertActiveComboboxOption(options[1])
+
+      // Select the option
+      await press(Keys.Enter)
+
+      // The active option is reset to the very first one
+      assertActiveComboboxOption(options[0])
+    })
+  )
 })
 
 describe('Form compatibility', () => {
diff --git a/packages/@headlessui-react/src/components/combobox/combobox.tsx b/packages/@headlessui-react/src/components/combobox/combobox.tsx
index efb19f45e9..6e40f0c253 100644
--- a/packages/@headlessui-react/src/components/combobox/combobox.tsx
+++ b/packages/@headlessui-react/src/components/combobox/combobox.tsx
@@ -488,6 +488,17 @@ function ComboboxFn<TValue, TTag extends ElementType = typeof DEFAULT_COMBOBOX_T
     [value, defaultValue, disabled, multiple, nullable, __demoMode, state]
   )
 
+  let lastActiveOption = useRef(
+    data.activeOptionIndex !== null ? data.options[data.activeOptionIndex] : null
+  )
+  useEffect(() => {
+    let currentActiveOption =
+      data.activeOptionIndex !== null ? data.options[data.activeOptionIndex] : null
+    if (lastActiveOption.current !== currentActiveOption) {
+      lastActiveOption.current = currentActiveOption
+    }
+  })
+
   useIsoMorphicEffect(() => {
     state.dataRef.current = data
   }, [data])
@@ -553,7 +564,22 @@ function ComboboxFn<TValue, TTag extends ElementType = typeof DEFAULT_COMBOBOX_T
 
   let registerOption = useEvent((id, dataRef) => {
     dispatch({ type: ActionTypes.RegisterOption, id, dataRef })
-    return () => dispatch({ type: ActionTypes.UnregisterOption, id })
+    return () => {
+      // When we are unregistering the currently active option, then we also have to make sure to
+      // reset the `defaultToFirstOption` flag, so that visually something is selected and the next
+      // time you press a key on your keyboard it will go to the proper next or previous option in
+      // the list.
+      //
+      // Since this was the active option and it could have been anywhere in the list, resetting to
+      // the very first option seems like a fine default. We _could_ be smarter about this by going
+      // to the previous / next item in list if we know the direction of the keyboard navigation,
+      // but that might be too complex/confusing from an end users perspective.
+      if (lastActiveOption.current?.id === id) {
+        defaultToFirstOption.current = true
+      }
+
+      dispatch({ type: ActionTypes.UnregisterOption, id })
+    }
   })
 
   let registerLabel = useEvent((id) => {
diff --git a/packages/@headlessui-vue/src/components/combobox/combobox.test.ts b/packages/@headlessui-vue/src/components/combobox/combobox.test.ts
index 13b8febdd3..0fd8168d95 100644
--- a/packages/@headlessui-vue/src/components/combobox/combobox.test.ts
+++ b/packages/@headlessui-vue/src/components/combobox/combobox.test.ts
@@ -5879,6 +5879,50 @@ describe('Multi-select', () => {
       assertComboboxOption(options[2], { selected: true })
     })
   )
+
+  it(
+    'should reset the active option, if the active option gets unmounted',
+    suppressConsoleLogs(async () => {
+      renderTemplate({
+        template: html`
+          <Combobox v-model="value" multiple>
+            <ComboboxInput />
+            <ComboboxButton>Trigger</ComboboxButton>
+            <ComboboxOptions>
+              <ComboboxOption
+                v-for="user in users.filter(p => !value.includes(p))"
+                :key="user"
+                :value="user"
+                >{{ user }}</ComboboxOption
+              >
+            </ComboboxOptions>
+          </Combobox>
+        `,
+        setup: () => {
+          let users = ['alice', 'bob', 'charlie']
+
+          let value = ref([])
+          return { users, value }
+        },
+      })
+
+      // Open combobox
+      await click(getComboboxButton())
+      assertCombobox({ state: ComboboxState.Visible })
+
+      let options = getComboboxOptions()
+
+      // Go to the next option
+      await press(Keys.ArrowDown)
+      assertActiveComboboxOption(options[1])
+
+      // Select the option
+      await press(Keys.Enter)
+
+      // The active option is reset to the very first one
+      assertActiveComboboxOption(options[0])
+    })
+  )
 })
 
 describe('Form compatibility', () => {
diff --git a/packages/@headlessui-vue/src/components/combobox/combobox.ts b/packages/@headlessui-vue/src/components/combobox/combobox.ts
index d608968866..820b50c803 100644
--- a/packages/@headlessui-vue/src/components/combobox/combobox.ts
+++ b/packages/@headlessui-vue/src/components/combobox/combobox.ts
@@ -391,6 +391,22 @@ export let Combobox = defineComponent({
         activationTrigger.value = ActivationTrigger.Other
       },
       unregisterOption(id: string) {
+        // When we are unregistering the currently active option, then we also have to make sure to
+        // reset the `defaultToFirstOption` flag, so that visually something is selected and the
+        // next time you press a key on your keyboard it will go to the proper next or previous
+        // option in the list.
+        //
+        // Since this was the active option and it could have been anywhere in the list, resetting
+        // to the very first option seems like a fine default. We _could_ be smarter about this by
+        // going to the previous / next item in list if we know the direction of the keyboard
+        // navigation, but that might be too complex/confusing from an end users perspective.
+        if (
+          api.activeOptionIndex.value !== null &&
+          api.options.value[api.activeOptionIndex.value]?.id === id
+        ) {
+          defaultToFirstOption.value = true
+        }
+
         let adjustedState = adjustOrderedState((options) => {
           let idx = options.findIndex((a) => a.id === id)
           if (idx !== -1) options.splice(idx, 1)