diff --git a/django/contrib/admin/static/admin/js/nav_sidebar.js b/django/contrib/admin/static/admin/js/nav_sidebar.js
index 86cb1cf837..261a9d4992 100644
--- a/django/contrib/admin/static/admin/js/nav_sidebar.js
+++ b/django/contrib/admin/static/admin/js/nav_sidebar.js
@@ -13,6 +13,12 @@
                 navLink.tabIndex = 0;
             }
         }
+        function disableNavFilterTabbing() {
+            document.getElementById('nav-filter').tabIndex = -1;
+        }
+        function enableNavFilterTabbing() {
+            document.getElementById('nav-filter').tabIndex = 0;
+        }
 
         const main = document.getElementById('main');
         let navSidebarIsOpen = localStorage.getItem('django.admin.navSidebarIsOpen');
@@ -21,6 +27,7 @@
         }
         if (navSidebarIsOpen === 'false') {
             disableNavLinkTabbing();
+            disableNavFilterTabbing();
         }
         main.classList.toggle('shifted', navSidebarIsOpen === 'true');
 
@@ -28,9 +35,11 @@
             if (navSidebarIsOpen === 'true') {
                 navSidebarIsOpen = 'false';
                 disableNavLinkTabbing();
+                disableNavFilterTabbing();
             } else {
                 navSidebarIsOpen = 'true';
                 enableNavLinkTabbing();
+                enableNavFilterTabbing();
             }
             localStorage.setItem('django.admin.navSidebarIsOpen', navSidebarIsOpen);
             main.classList.toggle('shifted');
diff --git a/docs/releases/4.0.5.txt b/docs/releases/4.0.5.txt
index b626f9ef36..15461a3f54 100644
--- a/docs/releases/4.0.5.txt
+++ b/docs/releases/4.0.5.txt
@@ -14,3 +14,6 @@ Bugfixes
 
 * Fixed a bug in Django 4.0 that caused a crash of ``QuerySet.filter()`` on
   ``IsNull()`` expressions (:ticket:`33705`).
+
+* Fixed a bug in Django 4.0 where a hidden quick filter toolbar in the admin's
+  navigation sidebar was focusable (:ticket:`33725`).
diff --git a/docs/spelling_wordlist b/docs/spelling_wordlist
index 29bc732dfe..fb3686f43c 100644
--- a/docs/spelling_wordlist
+++ b/docs/spelling_wordlist
@@ -170,6 +170,7 @@ filesystem
 filesystems
 flatpage
 flatpages
+focusable
 fooapp
 formatter
 formatters
diff --git a/tests/admin_views/test_nav_sidebar.py b/tests/admin_views/test_nav_sidebar.py
index a58193c550..994fdc4799 100644
--- a/tests/admin_views/test_nav_sidebar.py
+++ b/tests/admin_views/test_nav_sidebar.py
@@ -148,10 +148,14 @@ class SeleniumTests(AdminSeleniumTestCase):
         self.assertEqual(toggle_button.get_attribute("aria-label"), "Toggle navigation")
         for link in self.selenium.find_elements(By.CSS_SELECTOR, "#nav-sidebar a"):
             self.assertEqual(link.get_attribute("tabIndex"), "0")
+        filter_input = self.selenium.find_element_by_css_selector("#nav-filter")
+        self.assertEqual(filter_input.get_attribute("tabIndex"), "0")
         toggle_button.click()
         # Hidden sidebar is not reachable via keyboard navigation.
         for link in self.selenium.find_elements(By.CSS_SELECTOR, "#nav-sidebar a"):
             self.assertEqual(link.get_attribute("tabIndex"), "-1")
+        filter_input = self.selenium.find_element_by_css_selector("#nav-filter")
+        self.assertEqual(filter_input.get_attribute("tabIndex"), "-1")
         main_element = self.selenium.find_element(By.CSS_SELECTOR, "#main")
         self.assertNotIn("shifted", main_element.get_attribute("class").split())
 
@@ -188,9 +192,13 @@ class SeleniumTests(AdminSeleniumTestCase):
         # Hidden sidebar is not reachable via keyboard navigation.
         for link in self.selenium.find_elements(By.CSS_SELECTOR, "#nav-sidebar a"):
             self.assertEqual(link.get_attribute("tabIndex"), "-1")
+        filter_input = self.selenium.find_element_by_css_selector("#nav-filter")
+        self.assertEqual(filter_input.get_attribute("tabIndex"), "-1")
         toggle_button.click()
         for link in self.selenium.find_elements(By.CSS_SELECTOR, "#nav-sidebar a"):
             self.assertEqual(link.get_attribute("tabIndex"), "0")
+        filter_input = self.selenium.find_element_by_css_selector("#nav-filter")
+        self.assertEqual(filter_input.get_attribute("tabIndex"), "0")
         self.assertEqual(
             self.selenium.execute_script(
                 "return localStorage.getItem('django.admin.navSidebarIsOpen')"