diff --git a/Libraries/LibWeb/CMakeLists.txt b/Libraries/LibWeb/CMakeLists.txt
index cd1b1faa0a4..3bcf5fea40a 100644
--- a/Libraries/LibWeb/CMakeLists.txt
+++ b/Libraries/LibWeb/CMakeLists.txt
@@ -41,6 +41,7 @@ set(SOURCES
     ContentSecurityPolicy/Directives/DirectiveFactory.cpp
     ContentSecurityPolicy/Directives/DirectiveOperations.cpp
     ContentSecurityPolicy/Directives/FontSourceDirective.cpp
+    ContentSecurityPolicy/Directives/FrameSourceDirective.cpp
     ContentSecurityPolicy/Directives/KeywordSources.cpp
     ContentSecurityPolicy/Directives/Names.cpp
     ContentSecurityPolicy/Directives/SerializedDirective.cpp
diff --git a/Libraries/LibWeb/ContentSecurityPolicy/Directives/DirectiveFactory.cpp b/Libraries/LibWeb/ContentSecurityPolicy/Directives/DirectiveFactory.cpp
index cc4c72783c0..0f8a391a3fb 100644
--- a/Libraries/LibWeb/ContentSecurityPolicy/Directives/DirectiveFactory.cpp
+++ b/Libraries/LibWeb/ContentSecurityPolicy/Directives/DirectiveFactory.cpp
@@ -9,6 +9,7 @@
 #include <LibWeb/ContentSecurityPolicy/Directives/Directive.h>
 #include <LibWeb/ContentSecurityPolicy/Directives/DirectiveFactory.h>
 #include <LibWeb/ContentSecurityPolicy/Directives/FontSourceDirective.h>
+#include <LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.h>
 #include <LibWeb/ContentSecurityPolicy/Directives/Names.h>
 
 namespace Web::ContentSecurityPolicy::Directives {
@@ -21,6 +22,9 @@ GC::Ref<Directive> create_directive(GC::Heap& heap, String name, Vector<String>
     if (name == Names::FontSrc)
         return heap.allocate<FontSourceDirective>(move(name), move(value));
 
+    if (name == Names::FrameSrc)
+        return heap.allocate<FrameSourceDirective>(move(name), move(value));
+
     return heap.allocate<Directive>(move(name), move(value));
 }
 
diff --git a/Libraries/LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.cpp b/Libraries/LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.cpp
new file mode 100644
index 00000000000..163c3cc502d
--- /dev/null
+++ b/Libraries/LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.cpp
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2024, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/ContentSecurityPolicy/Directives/DirectiveOperations.h>
+#include <LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.h>
+#include <LibWeb/ContentSecurityPolicy/Directives/Names.h>
+#include <LibWeb/Fetch/Infrastructure/HTTP/Requests.h>
+
+namespace Web::ContentSecurityPolicy::Directives {
+
+GC_DEFINE_ALLOCATOR(FrameSourceDirective);
+
+FrameSourceDirective::FrameSourceDirective(String name, Vector<String> value)
+    : Directive(move(name), move(value))
+{
+}
+
+// https://w3c.github.io/webappsec-csp/#frame-src-pre-request
+Directive::Result FrameSourceDirective::pre_request_check(GC::Heap&, GC::Ref<Fetch::Infrastructure::Request const> request, GC::Ref<Policy const> policy) const
+{
+    // 1. Let name be the result of executing § 6.8.1 Get the effective directive for request on request.
+    auto name = get_the_effective_directive_for_request(request);
+
+    // 2. If the result of executing § 6.8.4 Should fetch directive execute on name, frame-src and policy is "No",
+    //    return "Allowed".
+    if (should_fetch_directive_execute(name, Names::FrameSrc, policy) == ShouldExecute::No)
+        return Result::Allowed;
+
+    // 3. If the result of executing § 6.7.2.5 Does request match source list? on request, this directive’s value,
+    //    and policy, is "Does Not Match", return "Blocked".
+    if (does_request_match_source_list(request, value(), policy) == MatchResult::DoesNotMatch)
+        return Result::Blocked;
+
+    // 4. Return "Allowed".
+    return Result::Allowed;
+}
+
+// https://w3c.github.io/webappsec-csp/#frame-src-post-request
+Directive::Result FrameSourceDirective::post_request_check(GC::Heap&, GC::Ref<Fetch::Infrastructure::Request const> request, GC::Ref<Fetch::Infrastructure::Response const> response, GC::Ref<Policy const> policy) const
+{
+    // 1. Let name be the result of executing § 6.8.1 Get the effective directive for request on request.
+    auto name = get_the_effective_directive_for_request(request);
+
+    // 2. If the result of executing § 6.8.4 Should fetch directive execute on name, frame-src and policy is "No",
+    //    return "Allowed".
+    if (should_fetch_directive_execute(name, Names::FrameSrc, policy) == ShouldExecute::No)
+        return Result::Allowed;
+
+    // 3. If the result of executing § 6.7.2.6 Does response to request match source list? on response, request, this
+    //    directive’s value, and policy, is "Does Not Match", return "Blocked".
+    if (does_response_match_source_list(response, request, value(), policy) == MatchResult::DoesNotMatch)
+        return Result::Blocked;
+
+    // 4. Return "Allowed".
+    return Result::Allowed;
+}
+
+}
diff --git a/Libraries/LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.h b/Libraries/LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.h
new file mode 100644
index 00000000000..14f6ac68772
--- /dev/null
+++ b/Libraries/LibWeb/ContentSecurityPolicy/Directives/FrameSourceDirective.h
@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2024, Luke Wilde <luke@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/ContentSecurityPolicy/Directives/Directive.h>
+
+namespace Web::ContentSecurityPolicy::Directives {
+
+// https://w3c.github.io/webappsec-csp/#directive-frame-src
+class FrameSourceDirective final : public Directive {
+    GC_CELL(FrameSourceDirective, Directive)
+    GC_DECLARE_ALLOCATOR(FrameSourceDirective);
+
+public:
+    virtual ~FrameSourceDirective() = default;
+
+    [[nodiscard]] virtual Result pre_request_check(GC::Heap&, GC::Ref<Fetch::Infrastructure::Request const>, GC::Ref<Policy const>) const override;
+    [[nodiscard]] virtual Result post_request_check(GC::Heap&, GC::Ref<Fetch::Infrastructure::Request const>, GC::Ref<Fetch::Infrastructure::Response const>, GC::Ref<Policy const>) const override;
+
+private:
+    FrameSourceDirective(String name, Vector<String> value);
+};
+
+}
diff --git a/Libraries/LibWeb/Forward.h b/Libraries/LibWeb/Forward.h
index c233dc80473..78e04083b23 100644
--- a/Libraries/LibWeb/Forward.h
+++ b/Libraries/LibWeb/Forward.h
@@ -133,6 +133,7 @@ namespace Web::ContentSecurityPolicy::Directives {
 class ConnectSourceDirective;
 class Directive;
 class FontSourceDirective;
+class FrameSourceDirective;
 struct SerializedDirective;
 
 }