diff --git a/public/locales/de-DE/translation.json b/public/locales/de-DE/translation.json
index 5f7d6a9..9aeec54 100644
--- a/public/locales/de-DE/translation.json
+++ b/public/locales/de-DE/translation.json
@@ -590,6 +590,9 @@
       "remove-from-group": "Aus Gruppe entfernen",
       "confirm-remove-from-group": "Möchten Sie den Benutzer wirklich aus dieser Gruppe entfernen?",
       "add-to-group": "Zur Gruppe hinzufügen",
+      "remove-from-tenant": "Aus Mandant entfernen",
+      "confirm-remove-from-tenant": "Möchten Sie den Benutzer wirklich aus diesem Mandanten entfernen?",
+      "add-to-tenant": "Zu Mandant hinzufügen",
       "no-tenants": "Der Benutzer ist derzeit kein Mitglied eines Mandanten.",
       "delete": "Benutzer löschen",
       "confirm-delete": "Möchten Sie diesen Benutzer wirklich löschen?"
diff --git a/public/locales/en-US/translation.json b/public/locales/en-US/translation.json
index ac20fbe..460fd59 100644
--- a/public/locales/en-US/translation.json
+++ b/public/locales/en-US/translation.json
@@ -590,6 +590,9 @@
       "remove-from-group": "Remove from group",
       "confirm-remove-from-group": "Do you really want to remove the user from this group?",
       "add-to-group": "Add to group",
+      "remove-from-tenant": "Remove from tenant",
+      "confirm-remove-from-tenant": "Do you really want to remove the user from this tenant?",
+      "add-to-tenant": "Add to tenant",
       "no-tenants": "User is currently not a member of any tenant.",
       "delete": "Delete User",
       "confirm-delete": "Do you really want to delete this user?"
diff --git a/src/pages/Admin.jsx b/src/pages/Admin.jsx
index 92ac95e..9bcfb42 100644
--- a/src/pages/Admin.jsx
+++ b/src/pages/Admin.jsx
@@ -656,7 +656,7 @@ const UserDetails = ({ user_id }) => {
     <UserProfile user_id={user_id} />
     <UserPassword user_id={user_id} />
     <UserGroups user_id={user_id} />
-    <UserTenants />
+    <UserTenants user_id={user_id} />
 
     <h3>{t("admin.danger-zone")}</h3>
     <div class="button-group">
@@ -823,10 +823,32 @@ const UserGroups = ({ user_id }) => {
   </>
 }
 
-const UserTenants = () => {
+const UserTenants = ({ user_id }) => {
   const
-    { api: { tenant: { by_member: tenants } } } = useContext(AppState),
-    [t] = useTranslation()
+    state = useContext(AppState),
+    { api: { tenant: { by_member: tenants } } } = state,
+    [t] = useTranslation(),
+    add_open = useSignal(false),
+    remove_open = useSignal(false),
+    pending_remove = useSignal(null),
+    new_tenant = useSignal('')
+
+  const
+    refetch = () => engine_rest.tenant.by_member(state, user_id),
+    confirm_remove = (tenant_id) => {
+      pending_remove.value = tenant_id
+      remove_open.value = true
+    },
+    do_remove = () =>
+      void engine_rest.tenant.remove_user(state, pending_remove.value, user_id).then(refetch),
+    do_add = e => {
+      e.preventDefault()
+      void engine_rest.tenant.add_user(state, new_tenant.value, user_id).then(() => {
+        new_tenant.value = ''
+        add_open.value = false
+        refetch()
+      })
+    }
 
   return <>
     <h3>{t("admin.tenants")}</h3>
@@ -838,6 +860,7 @@ const UserTenants = () => {
           <tr>
             <th>{t("common.id")}</th>
             <th>{t("common.name")}</th>
+            <th>{t("common.action")}</th>
           </tr>
           </thead>
           <tbody>
@@ -845,11 +868,31 @@ const UserTenants = () => {
             <tr key={tenant.id}>
               <td>{tenant.id}</td>
               <td>{tenant.name}</td>
+              <td><button class="danger" onClick={() => confirm_remove(tenant.id)}>{t("admin.user.remove-from-tenant")}</button></td>
             </tr>
           ))}
           </tbody>
         </table>
         : <p>{t("admin.user.no-tenants")}</p>} />
+
+    <div class="button-group">
+      <button onClick={() => (add_open.value = true)}>{t("admin.user.add-to-tenant")}</button>
+    </div>
+
+    <Dialog open={add_open} title={t("admin.user.add-to-tenant")}>
+      <form onSubmit={do_add}>
+        <label for="add-tenant-id">{t("admin.tenant.tenant-id")}</label>
+        <input id="add-tenant-id" type="text" value={new_tenant.value}
+               onInput={(e) => (new_tenant.value = e.currentTarget.value)} required />
+        <div class="button-group">
+          <button type="submit">{t("common.save")}</button>
+          <button type="button" class="secondary" onClick={() => (add_open.value = false)}>{t("common.cancel")}</button>
+        </div>
+      </form>
+    </Dialog>
+
+    <ConfirmDialog open={remove_open} confirm_label={t("common.remove")}
+                   message={t("admin.user.confirm-remove-from-tenant")} on_confirm={do_remove} />
   </>
 }
 
diff --git a/src/pages/Admin.test.jsx b/src/pages/Admin.test.jsx
index 250f5d9..9690d23 100644
--- a/src/pages/Admin.test.jsx
+++ b/src/pages/Admin.test.jsx
@@ -177,6 +177,39 @@ describe("AdminPage", () => {
       expect(engine_rest.user.delete.mock.lastCall[0]).toBe(state);
       expect(engine_rest.user.delete.mock.lastCall[1]).toBe("jdoe");
     });
+
+    it("adds a tenant membership from the user details page", () => {
+      mockParams = { page_id: "users", selection_id: "jdoe" };
+      const { container, getAllByText } = renderPage(state);
+
+      fireEvent.click(getAllByText("admin.user.add-to-tenant")[0]);
+      const input = container.querySelector("#add-tenant-id");
+      fireEvent.input(input, { target: { value: "tenant-a" } });
+      fireEvent.submit(input.closest("form"));
+
+      expect(engine_rest.tenant.add_user).toHaveBeenCalled();
+      const call = engine_rest.tenant.add_user.mock.lastCall;
+      expect(call[0]).toBe(state);
+      expect(call[1]).toBe("tenant-a");
+      expect(call[2]).toBe("jdoe");
+    });
+
+    it("removes a tenant membership from the user details page", () => {
+      mockParams = { page_id: "users", selection_id: "jdoe" };
+      signal_response(state.api.tenant.by_member, [
+        { id: "tenant-a", name: "Tenant A" },
+      ]);
+      const { container, getByText } = renderPage(state);
+
+      fireEvent.click(getByText("admin.user.remove-from-tenant"));
+      fireEvent.click(container.querySelector("dialog[open] button.danger"));
+
+      expect(engine_rest.tenant.remove_user).toHaveBeenCalled();
+      const call = engine_rest.tenant.remove_user.mock.lastCall;
+      expect(call[0]).toBe(state);
+      expect(call[1]).toBe("tenant-a");
+      expect(call[2]).toBe("jdoe");
+    });
   });
 
   describe("Groups", () => {