diff --git a/browser/components/BrowserContentHandler.sys.mjs b/browser/components/BrowserContentHandler.sys.mjs
index cbb08449bb7cf..e67ff242494d4 100644
--- a/browser/components/BrowserContentHandler.sys.mjs
+++ b/browser/components/BrowserContentHandler.sys.mjs
@@ -1018,6 +1018,7 @@ function maybeRecordToHandleTelemetry(uri, isLaunch) {
       ".xhtml",
       ".svg",
       ".webp",
+      ".jxl",
     ]);
     if (registeredExtensions.has(extension)) {
       Services.telemetry.keyedScalarAdd(scalar, extension, 1);
diff --git a/browser/installer/windows/msix/AppxManifest.xml.in b/browser/installer/windows/msix/AppxManifest.xml.in
index 9fc8e2902d4aa..a3b38e504b7c4 100644
--- a/browser/installer/windows/msix/AppxManifest.xml.in
+++ b/browser/installer/windows/msix/AppxManifest.xml.in
@@ -66,6 +66,7 @@
               <uap:FileType>.xhtml</uap:FileType>
               <uap:FileType>.svg</uap:FileType>
               <uap:FileType>.webp</uap:FileType>
+              <uap:FileType>.jxl</uap:FileType>
             </uap:SupportedFileTypes>
             <uap:Logo>Assets\Document44x44.png</uap:Logo>
             <uap2:SupportedVerbs>
diff --git a/browser/installer/windows/nsis/shared.nsh b/browser/installer/windows/nsis/shared.nsh
index 2058b4944caf3..f803348dc7a10 100755
--- a/browser/installer/windows/nsis/shared.nsh
+++ b/browser/installer/windows/nsis/shared.nsh
@@ -544,6 +544,7 @@ ${RemoveDefaultBrowserAgentShortcut}
   ${AddAssociationIfNoneExist} ".svg" "WaterfoxHTML$5"
   ${AddAssociationIfNoneExist} ".webp"  "WaterfoxHTML$5"
   ${AddAssociationIfNoneExist} ".avif" "WaterfoxHTML$5"
+  ${AddAssociationIfNoneExist} ".jxl" "WaterfoxHTML$5"
 
   ${AddAssociationIfNoneExist} ".pdf" "WaterfoxPDF$5"
 
diff --git a/browser/installer/windows/nsis/uninstaller.nsi b/browser/installer/windows/nsis/uninstaller.nsi
index 9e9fb53bec614..bc109b450ed1f 100755
--- a/browser/installer/windows/nsis/uninstaller.nsi
+++ b/browser/installer/windows/nsis/uninstaller.nsi
@@ -497,7 +497,9 @@ Section "Uninstall"
   ${un.RegCleanFileHandler}  ".ogv"   "WaterfoxHTML-$AppUserModelID"
   ${un.RegCleanFileHandler}  ".webm"  "WaterfoxHTML-$AppUserModelID"
   ${un.RegCleanFileHandler}  ".svg"   "WaterfoxHTML-$AppUserModelID"
+  ${un.RegCleanFileHandler}  ".webp"  "WaterfoxHTML-$AppUserModelID"
   ${un.RegCleanFileHandler}  ".avif"  "WaterfoxHTML-$AppUserModelID"
+  ${un.RegCleanFileHandler}  ".jxl"   "WaterfoxHTML-$AppUserModelID"
 
   ${un.RegCleanFileHandler}  ".pdf"   "WaterfoxPDF-$AppUserModelID"
 
diff --git a/third_party/rust/mime_guess/src/mime_types.rs b/third_party/rust/mime_guess/src/mime_types.rs
index 13c91b7bee77a..d5256c108959b 100644
--- a/third_party/rust/mime_guess/src/mime_types.rs
+++ b/third_party/rust/mime_guess/src/mime_types.rs
@@ -567,6 +567,7 @@ pub static MIME_TYPES: &[(&str, &[&str])] = &[
     ("jsonml", &["application/jsonml+json"]),
     ("jsx", &["text/jscript"]),
     ("jsxbin", &["text/plain"]),
+    ("jxl", &["image/jxl"]),
     ("kar", &["audio/midi"]),
     ("karbon", &["application/vnd.kde.karbon"]),
     ("kfo", &["application/vnd.kde.kformula"]),
diff --git a/toolkit/components/downloads/DownloadList.sys.mjs b/toolkit/components/downloads/DownloadList.sys.mjs
index 695b611dc87f0..0e7b2983b5bd8 100644
--- a/toolkit/components/downloads/DownloadList.sys.mjs
+++ b/toolkit/components/downloads/DownloadList.sys.mjs
@@ -50,6 +50,7 @@ const FILE_EXTENSIONS = [
   "jpg",
   "jpeg",
   "json",
+  "jxl",
   "m4a",
   "mdb",
   "mid",
diff --git a/toolkit/components/extensions/parent/ext-downloads.js b/toolkit/components/extensions/parent/ext-downloads.js
index 10c99534c4e0d..1b35efcc8f364 100644
--- a/toolkit/components/extensions/parent/ext-downloads.js
+++ b/toolkit/components/extensions/parent/ext-downloads.js
@@ -103,6 +103,8 @@ const FILTER_IMAGES_EXTENSIONS = [
   "psd",
   "raw",
   "webp",
+  "avif",
+  "jxl",
 ];
 
 const FILTER_XML_EXTENSIONS = ["xml"];
diff --git a/toolkit/content/filepicker.properties b/toolkit/content/filepicker.properties
index 27b8f4a8fc66d..7555a8b6e5023 100644
--- a/toolkit/content/filepicker.properties
+++ b/toolkit/content/filepicker.properties
@@ -5,7 +5,7 @@
 allFilter=*
 htmlFilter=*.html; *.htm; *.shtml; *.xhtml
 textFilter=*.txt; *.text
-imageFilter=*.jpe; *.jpg; *.jpeg; *.gif; *.png; *.bmp; *.ico; *.svg; *.svgz; *.tif; *.tiff; *.ai; *.drw; *.pct; *.psp; *.xcf; *.psd; *.raw; *.webp
+imageFilter=*.jpe; *.jpg; *.jpeg; *.gif; *.png; *.bmp; *.ico; *.svg; *.svgz; *.tif; *.tiff; *.ai; *.drw; *.pct; *.psp; *.xcf; *.psd; *.raw; *.webp; *.avif; *.jxl
 xmlFilter=*.xml
 xulFilter=*.xul
 audioFilter=*.aac; *.aif; *.flac; *.iff; *.m4a; *.m4b; *.mid; *.midi; *.mp3; *.mpa; *.mpc; *.oga; *.ogg; *.opus; *.ra; *.ram; *.snd; *.wav; *.wma
diff --git a/widget/gtk/nsAppShell.cpp b/widget/gtk/nsAppShell.cpp
index bea837605fe01..3a0adf523f552 100644
--- a/widget/gtk/nsAppShell.cpp
+++ b/widget/gtk/nsAppShell.cpp
@@ -369,7 +369,8 @@ nsresult nsAppShell::Init() {
     gchar* name = gdk_pixbuf_format_get_name(format);
     if (strcmp(name, "jpeg") && strcmp(name, "png") && strcmp(name, "gif") &&
         strcmp(name, "bmp") && strcmp(name, "ico") && strcmp(name, "xpm") &&
-        strcmp(name, "svg") && strcmp(name, "webp") && strcmp(name, "avif")) {
+        strcmp(name, "svg") && strcmp(name, "webp") && strcmp(name, "avif") &&
+        strcmp(name, "jxl")) {
       gdk_pixbuf_format_set_disabled(format, TRUE);
     }
     g_free(name);