diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index 732ed3ebbfb9..a2686e6bbfe2 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -452,7 +452,7 @@ pref("browser.download.alwaysOpenInSystemViewerContextMenuItem", true);
 // Open downloaded file types internally for the given types.
 // This is a comma-separated list, the empty string ("") means no types are
 // viewable internally.
-pref("browser.download.viewableInternally.enabledTypes", "xml,svg,webp,avif");
+pref("browser.download.viewableInternally.enabledTypes", "xml,svg,webp,avif,jxl");
 
 
 // This controls whether the button is automatically shown/hidden depending
diff --git a/browser/components/downloads/DownloadsViewableInternally.jsm b/browser/components/downloads/DownloadsViewableInternally.jsm
index 0860f3e56e22..c675c99858f0 100644
--- a/browser/components/downloads/DownloadsViewableInternally.jsm
+++ b/browser/components/downloads/DownloadsViewableInternally.jsm
@@ -161,6 +161,20 @@ let DownloadsViewableInternally = {
       },
       // available getter is set by initAvailable()
     },
+    {
+      extension: "jxl",
+      mimeTypes: ["image/jxl"],
+      initAvailable() {
+        XPCOMUtils.defineLazyPreferenceGetter(
+          this,
+          "available",
+          "image.jxl.enabled",
+          false,
+          () => DownloadsViewableInternally._updateHandler(this)
+        );
+      },
+      // available getter is set by initAvailable()
+    },
     {
       extension: "pdf",
       mimeTypes: ["application/pdf"],
diff --git a/dom/tests/browser/browser_persist_image_accept.js b/dom/tests/browser/browser_persist_image_accept.js
index fc9b8c8e6d22..f3de9e379d58 100644
--- a/dom/tests/browser/browser_persist_image_accept.js
+++ b/dom/tests/browser/browser_persist_image_accept.js
@@ -50,6 +50,7 @@ function expectedImageAcceptHeader() {
 
   return (
     (Services.prefs.getBoolPref("image.avif.enabled") ? "image/avif," : "") +
+    (Services.prefs.getBoolPref("image.jxl.enabled") ? "image/jxl," : "") +
     (Services.prefs.getBoolPref("image.webp.enabled") ? "image/webp," : "") +
     "*/*"
   );
diff --git a/netwerk/protocol/http/nsHttpHandler.cpp b/netwerk/protocol/http/nsHttpHandler.cpp
index 402c43d9e11f..26f7bed0ad94 100644
--- a/netwerk/protocol/http/nsHttpHandler.cpp
+++ b/netwerk/protocol/http/nsHttpHandler.cpp
@@ -188,6 +188,10 @@ static nsCString ImageAcceptHeader() {
     mimeTypes.Append("image/avif,");
   }
 
+  if (mozilla::StaticPrefs::image_jxl_enabled()) {
+    mimeTypes.Append("image/jxl,");
+  }
+
   if (mozilla::StaticPrefs::image_webp_enabled()) {
     mimeTypes.Append("image/webp,");
   }
@@ -355,6 +359,7 @@ static const char* gCallbackPrefs[] = {
     DOM_SECURITY_PREFIX,
     "image.http.accept",
     "image.avif.enabled",
+    "image.jxl.enabled",
     "image.webp.enabled",
     nullptr,
 };
@@ -1831,6 +1836,7 @@ void nsHttpHandler::PrefsChanged(const char* pref) {
 
   const bool imageAcceptPrefChanged = PREF_CHANGED("image.http.accept") ||
                                       PREF_CHANGED("image.avif.enabled") ||
+                                      PREF_CHANGED("image.jxl.enabled") ||
                                       PREF_CHANGED("image.webp.enabled");
 
   if (imageAcceptPrefChanged) {