diff --git a/src/browser/js/bridge.zig b/src/browser/js/bridge.zig
index fb49e01e..9d4d6310 100644
--- a/src/browser/js/bridge.zig
+++ b/src/browser/js/bridge.zig
@@ -853,6 +853,7 @@ pub const JsApis = flattenTypes(&.{
     @import("../webapi/event/InputEvent.zig"),
     @import("../webapi/event/PromiseRejectionEvent.zig"),
     @import("../webapi/event/SubmitEvent.zig"),
+    @import("../webapi/event/FormDataEvent.zig"),
     @import("../webapi/MessageChannel.zig"),
     @import("../webapi/MessagePort.zig"),
     @import("../webapi/media/MediaError.zig"),
diff --git a/src/browser/tests/net/form_data.html b/src/browser/tests/net/form_data.html
index 12363038..fdfe4bc1 100644
--- a/src/browser/tests/net/form_data.html
+++ b/src/browser/tests/net/form_data.html
@@ -734,3 +734,101 @@
   testing.expectEqual([['field', 'data'], ['x', '0'], ['y', '0']], entries);
 }
 </script>
+
+<script id=formDataEventFires>
+{
+  // formdata event fires on the form when FormData is constructed with a form
+  const form = document.createElement('form');
+
+  const input = document.createElement('input');
+  input.name = 'field';
+  input.value = 'hello';
+  form.appendChild(input);
+
+  let eventFired = false;
+  let receivedFormData = null;
+
+  form.addEventListener('formdata', (e) => {
+    eventFired = true;
+    receivedFormData = e.formData;
+  });
+
+  const fd = new FormData(form);
+  testing.expectEqual(true, eventFired);
+  testing.expectEqual(fd, receivedFormData);
+}
+</script>
+
+<script id=formDataEventNotFiredWithoutForm>
+{
+  // formdata event should NOT fire when FormData is constructed without a form
+  const fd = new FormData();
+  fd.append('a', '1');
+  testing.expectEqual('1', fd.get('a'));
+}
+</script>
+
+<script id=formDataEventBubbles>
+{
+  // formdata event should bubble
+  const container = document.createElement('div');
+  const form = document.createElement('form');
+  container.appendChild(form);
+  document.body.appendChild(container);
+
+  const input = document.createElement('input');
+  input.name = 'x';
+  input.value = '1';
+  form.appendChild(input);
+
+  let bubbled = false;
+  container.addEventListener('formdata', () => {
+    bubbled = true;
+  });
+
+  const fd = new FormData(form);
+  testing.expectEqual(true, bubbled);
+
+  document.body.removeChild(container);
+}
+</script>
+
+<script id=formDataEventNotCancelable>
+{
+  // formdata event should not be cancelable
+  const form = document.createElement('form');
+
+  const input = document.createElement('input');
+  input.name = 'key';
+  input.value = 'val';
+  form.appendChild(input);
+
+  let cancelable = null;
+  form.addEventListener('formdata', (e) => {
+    cancelable = e.cancelable;
+  });
+
+  const fd = new FormData(form);
+  testing.expectEqual(false, cancelable);
+}
+</script>
+
+<script id=formDataEventModifyFormData>
+{
+  // Listeners can modify formData during the event
+  const form = document.createElement('form');
+
+  const input = document.createElement('input');
+  input.name = 'original';
+  input.value = 'data';
+  form.appendChild(input);
+
+  form.addEventListener('formdata', (e) => {
+    e.formData.append('added', 'by-listener');
+  });
+
+  const fd = new FormData(form);
+  testing.expectEqual('data', fd.get('original'));
+  testing.expectEqual('by-listener', fd.get('added'));
+}
+</script>
diff --git a/src/browser/webapi/Event.zig b/src/browser/webapi/Event.zig
index bbac984d..54a53d7e 100644
--- a/src/browser/webapi/Event.zig
+++ b/src/browser/webapi/Event.zig
@@ -77,6 +77,7 @@ pub const Type = union(enum) {
     ui_event: *@import("event/UIEvent.zig"),
     promise_rejection_event: *@import("event/PromiseRejectionEvent.zig"),
     submit_event: *@import("event/SubmitEvent.zig"),
+    form_data_event: *@import("event/FormDataEvent.zig"),
 };
 
 pub const Options = struct {
@@ -176,6 +177,7 @@ pub fn is(self: *Event, comptime T: type) ?*T {
         .pop_state_event => |e| return if (T == @import("event/PopStateEvent.zig")) e else null,
         .promise_rejection_event => |e| return if (T == @import("event/PromiseRejectionEvent.zig")) e else null,
         .submit_event => |e| return if (T == @import("event/SubmitEvent.zig")) e else null,
+        .form_data_event => |e| return if (T == @import("event/FormDataEvent.zig")) e else null,
         .ui_event => |e| {
             if (T == @import("event/UIEvent.zig")) {
                 return e;
diff --git a/src/browser/webapi/event/FormDataEvent.zig b/src/browser/webapi/event/FormDataEvent.zig
new file mode 100644
index 00000000..6947aeab
--- /dev/null
+++ b/src/browser/webapi/event/FormDataEvent.zig
@@ -0,0 +1,95 @@
+// Copyright (C) 2023-2026 Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const String = @import("../../../string.zig").String;
+const Page = @import("../../Page.zig");
+const Session = @import("../../Session.zig");
+const js = @import("../../js/js.zig");
+
+const Event = @import("../Event.zig");
+const UIEvent = @import("UIEvent.zig");
+
+const FormData = @import("../net/FormData.zig");
+
+/// https://developer.mozilla.org/en-US/docs/Web/API/FormDataEvent
+const FormDataEvent = @This();
+
+_proto: *Event,
+_form_data: ?*FormData = null,
+
+const Options = Event.inheritOptions(FormDataEvent, struct {
+    formData: ?*FormData = null,
+});
+
+pub fn init(typ: []const u8, maybe_options: Options, page: *Page) !*FormDataEvent {
+    const arena = try page.getArena(.{ .debug = "FormDataEvent" });
+    errdefer page.releaseArena(arena);
+    const type_string = try String.init(arena, typ, .{});
+    return initWithTrusted(arena, type_string, maybe_options, false, page);
+}
+
+pub fn initTrusted(typ: String, _opts: ?Options, page: *Page) !*FormDataEvent {
+    const arena = try page.getArena(.{ .debug = "FormDataEvent.trusted" });
+    errdefer page.releaseArena(arena);
+    return initWithTrusted(arena, typ, _opts, true, page);
+}
+
+fn initWithTrusted(arena: Allocator, typ: String, maybe_options: ?Options, trusted: bool, page: *Page) !*FormDataEvent {
+    const options = maybe_options orelse Options{};
+
+    const event = try page._factory.event(
+        arena,
+        typ,
+        FormDataEvent{
+            ._proto = undefined,
+            ._form_data = options.formData,
+        },
+    );
+
+    Event.populatePrototypes(event, options, trusted);
+    return event;
+}
+
+pub fn deinit(self: *FormDataEvent, shutdown: bool, session: *Session) void {
+    self._proto.deinit(shutdown, session);
+}
+
+pub fn asEvent(self: *FormDataEvent) *Event {
+    return self._proto;
+}
+
+pub fn getFormData(self: *const FormDataEvent) ?*FormData {
+    return self._form_data;
+}
+
+pub const JsApi = struct {
+    pub const bridge = js.Bridge(FormDataEvent);
+
+    pub const Meta = struct {
+        pub const name = "FormDataEvent";
+        pub const prototype_chain = bridge.prototypeChain();
+        pub var class_id: bridge.ClassId = undefined;
+        pub const weak = true;
+        pub const finalizer = bridge.finalizer(FormDataEvent.deinit);
+    };
+
+    pub const constructor = bridge.constructor(FormDataEvent.init, .{});
+    pub const formData = bridge.accessor(FormDataEvent.getFormData, null, .{});
+};
diff --git a/src/browser/webapi/event/SubmitEvent.zig b/src/browser/webapi/event/SubmitEvent.zig
index 80cb4d36..fbb1af06 100644
--- a/src/browser/webapi/event/SubmitEvent.zig
+++ b/src/browser/webapi/event/SubmitEvent.zig
@@ -26,7 +26,7 @@ const Event = @import("../Event.zig");
 const HtmlElement = @import("../element/Html.zig");
 const Allocator = std.mem.Allocator;
 
-// https://developer.mozilla.org/en-US/docs/Web/API/SubmitEvent
+/// https://developer.mozilla.org/en-US/docs/Web/API/SubmitEvent
 const SubmitEvent = @This();
 
 _proto: *Event,
diff --git a/src/browser/webapi/net/FormData.zig b/src/browser/webapi/net/FormData.zig
index 69246f93..73a5a5c8 100644
--- a/src/browser/webapi/net/FormData.zig
+++ b/src/browser/webapi/net/FormData.zig
@@ -35,10 +35,22 @@ _arena: Allocator,
 _list: KeyValueList,
 
 pub fn init(form: ?*Form, submitter: ?*Element, page: *Page) !*FormData {
-    return page._factory.create(FormData{
+    const form_data = try page._factory.create(FormData{
         ._arena = page.arena,
         ._list = try collectForm(page.arena, form, submitter, page),
     });
+
+    // Dispatch `formdata` event if form provided.
+    if (form) |_form| {
+        const form_data_event = try (@import("../event/FormDataEvent.zig")).initTrusted(
+            comptime .wrap("formdata"),
+            .{ .bubbles = true, .cancelable = false, .formData = form_data },
+            page,
+        );
+        try page._event_manager.dispatch(_form.asNode().asEventTarget(), form_data_event.asEvent());
+    }
+
+    return form_data;
 }
 
 pub fn get(self: *const FormData, name: []const u8) ?[]const u8 {