diff --git a/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp b/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
index 862fe0971a..5fe40c7c8d 100644
--- a/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
+++ b/Libraries/LibWeb/HTML/WindowOrWorkerGlobalScope.cpp
@@ -2,7 +2,7 @@
  * Copyright (c) 2022, Andrew Kaster <akaster@serenityos.org>
  * Copyright (c) 2023, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2023, Luke Wilde <lukew@serenityos.org>
- * Copyright (c) 2025, Shannon Booth <shannon@serenityos.org>
+ * Copyright (c) 2025-2026, Shannon Booth <shannon@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
diff --git a/Libraries/LibWeb/Internals/Internals.cpp b/Libraries/LibWeb/Internals/Internals.cpp
index 11e7123295..2328b09630 100644
--- a/Libraries/LibWeb/Internals/Internals.cpp
+++ b/Libraries/LibWeb/Internals/Internals.cpp
@@ -9,6 +9,7 @@
 #include <LibGfx/Cursor.h>
 #include <LibJS/Runtime/Date.h>
 #include <LibJS/Runtime/VM.h>
+#include <LibURL/Parser.h>
 #include <LibUnicode/TimeZone.h>
 #include <LibWeb/ARIA/AriaData.h>
 #include <LibWeb/ARIA/StateAndProperties.h>
@@ -532,4 +533,10 @@ void Internals::clear_element(HTML::HTMLElement& element)
     form_associated_element.clear_algorithm();
 }
 
+void Internals::set_environments_top_level_url(StringView url)
+{
+    auto& realm = *vm().current_realm();
+    HTML::principal_realm_settings_object(realm).top_level_creation_url = URL::Parser::basic_parse(url);
+}
+
 }
diff --git a/Libraries/LibWeb/Internals/Internals.h b/Libraries/LibWeb/Internals/Internals.h
index a299738b14..74d81f45e5 100644
--- a/Libraries/LibWeb/Internals/Internals.h
+++ b/Libraries/LibWeb/Internals/Internals.h
@@ -105,6 +105,7 @@ public:
     void set_highlighted_node(GC::Ptr<DOM::Node> node);
 
     void clear_element(HTML::HTMLElement&);
+    void set_environments_top_level_url(StringView url);
 
 private:
     explicit Internals(JS::Realm&);
diff --git a/Libraries/LibWeb/Internals/Internals.idl b/Libraries/LibWeb/Internals/Internals.idl
index 5ff01ad3ac..86115cc0ca 100644
--- a/Libraries/LibWeb/Internals/Internals.idl
+++ b/Libraries/LibWeb/Internals/Internals.idl
@@ -79,6 +79,8 @@ interface Internals {
 
     undefined handleSDLInputEvents();
 
+    undefined setEnvironmentsTopLevelURL(USVString url);
+
     InternalGamepad connectVirtualGamepad();
 
     undefined setHighlightedNode(Node? node);
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
index da7e523ddd..485e691c93 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/BindingsGenerator/IDLGenerators.cpp
@@ -3731,11 +3731,21 @@ void @class_name@::initialize(JS::Realm& realm)
             continue;
 
         auto attribute_generator = generator_for_member(attribute.name, attribute.extended_attributes);
+
+        if (attribute.extended_attributes.contains("SecureContext")) {
+            attribute_generator.append(R"~~~(
+    if (HTML::is_secure_context(Bindings::principal_host_defined_environment_settings_object(realm))) {)~~~");
+        }
+
         if (attribute.extended_attributes.contains("FIXME")) {
             attribute_generator.set("attribute.name", attribute.name);
             attribute_generator.append(R"~~~(
     @define_direct_property@("@attribute.name@"_utf16_fly_string, JS::js_undefined(), default_attributes | JS::Attribute::Unimplemented);
             )~~~");
+            if (attribute.extended_attributes.contains("SecureContext")) {
+                attribute_generator.append(R"~~~(
+    })~~~");
+            }
             continue;
         }
 
@@ -3778,6 +3788,11 @@ void @class_name@::initialize(JS::Realm& realm)
         attribute_generator.append(R"~~~(
     @define_direct_accessor@("@attribute.name@"_utf16_fly_string, native_@attribute.getter_callback@, native_@attribute.setter_callback@, default_attributes);
 )~~~");
+
+        if (attribute.extended_attributes.contains("SecureContext")) {
+            attribute_generator.append(R"~~~(
+    })~~~");
+        }
     }
 
     for (auto& function : interface.functions) {
@@ -3823,6 +3838,11 @@ void @class_name@::initialize(JS::Realm& realm)
         function_generator.set("function.name:snakecase", make_input_acceptable_cpp(overload_set.key.to_snakecase()));
         function_generator.set("function.length", ByteString::number(get_shortest_function_length(overload_set.value)));
 
+        if (function.extended_attributes.contains("SecureContext")) {
+            function_generator.append(R"~~~(
+    if (HTML::is_secure_context(Bindings::principal_host_defined_environment_settings_object(realm))) {)~~~");
+        }
+
         if (any_of(overload_set.value, [](auto const& function) { return function.extended_attributes.contains("Unscopable"); })) {
             VERIFY(all_of(overload_set.value, [](auto const& function) { return function.extended_attributes.contains("Unscopable"); }));
             function_generator.append(R"~~~(
@@ -3833,6 +3853,11 @@ void @class_name@::initialize(JS::Realm& realm)
         function_generator.append(R"~~~(
     @define_native_function@(realm, "@function.name@"_utf16_fly_string, @function.name:snakecase@, @function.length@, default_attributes);
 )~~~");
+
+        if (function.extended_attributes.contains("SecureContext")) {
+            function_generator.append(R"~~~(
+    })~~~");
+        }
     }
 
     bool should_generate_stringifier = true;
@@ -5548,6 +5573,7 @@ void generate_prototype_implementation(IDL::Interface const& interface, StringBu
 #include <LibURL/Origin.h>
 #include <LibWeb/Bindings/@prototype_class@.h>
 #include <LibWeb/Bindings/ExceptionOrUtils.h>
+#include <LibWeb/Bindings/PrincipalHostDefined.h>
 #include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/DOM/Element.h>
 #include <LibWeb/DOM/Event.h>
@@ -5969,6 +5995,7 @@ void generate_global_mixin_implementation(IDL::Interface const& interface, Strin
 #include <LibWeb/Bindings/@prototype_name@.h>
 #include <LibWeb/Bindings/ExceptionOrUtils.h>
 #include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/PrincipalHostDefined.h>
 #include <LibWeb/DOM/Element.h>
 #include <LibWeb/DOM/Event.h>
 #include <LibWeb/DOM/IDLEventListener.h>
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
index 1542bcc084..6c982ab57a 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWindowOrWorkerInterfaces.cpp
@@ -120,6 +120,7 @@ static ErrorOr<void> generate_intrinsic_definitions_implementation(StringView ou
 #include <LibGC/DeferGC.h>
 #include <LibJS/Runtime/Object.h>
 #include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/PrincipalHostDefined.h>
 #include <LibWeb/Export.h>
 #include <LibWeb/HTML/Window.h>
 #include <LibWeb/HTML/DedicatedWorkerGlobalScope.h>
@@ -182,6 +183,27 @@ void Intrinsics::create_web_namespace<@namespace_class@>(JS::Realm& realm)
 )~~~");
     };
 
+    generator.append(R"~~~(
+static bool is_secure_context_interface(InterfaceName name)
+{
+    switch (name) {
+)~~~");
+    for (auto const& interface : interface_sets.intrinsics) {
+        if (!interface.extended_attributes.contains("SecureContext"))
+            continue;
+
+        generator.set("secure_context_interface_name", interface.name);
+        generator.append(R"~~~(
+    case InterfaceName::@secure_context_interface_name@:)~~~");
+    }
+    generator.append(R"~~~(
+        return true;
+    default:
+        return false;
+    }
+}
+)~~~");
+
     auto generate_global_exposed = [&generator](StringView global_name, Vector<IDL::Interface&> const& interface_set) {
         generator.set("global_name", global_name);
         generator.append(R"~~~(
@@ -235,8 +257,11 @@ bool is_exposed(InterfaceName name, JS::Realm& realm)
         TODO(); // FIXME: ServiceWorkerGlobalScope and WorkletGlobalScope.
     }
 
-    // FIXME: 2. If realm’s settings object is not a secure context, and construct is conditionally exposed on
-    //           [SecureContext], then return false.
+    // 2. If realm’s settings object is not a secure context, and construct is conditionally exposed on
+    //    [SecureContext], then return false.
+    if (is_secure_context_interface(name) && HTML::is_non_secure_context(principal_host_defined_environment_settings_object(realm)))
+        return false;
+
     // FIXME: 3. If realm’s settings object’s cross-origin isolated capability is false, and construct is
     //           conditionally exposed on [CrossOriginIsolated], then return false.
 
@@ -352,6 +377,7 @@ static ErrorOr<void> generate_exposed_interface_implementation(StringView class_
 #include <LibJS/Runtime/Object.h>
 #include <LibWeb/Bindings/Intrinsics.h>
 #include <LibWeb/Bindings/@global_object_name@ExposedInterfaces.h>
+#include <LibWeb/HTML/Scripting/Environments.h>
 )~~~");
     for (auto& interface : exposed_interfaces) {
         auto gen = generator.fork();
@@ -382,6 +408,7 @@ namespace Web::Bindings {
 void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global)
 {
     static constexpr u8 attr = JS::Attribute::Writable | JS::Attribute::Configurable;
+    [[maybe_unused]] bool is_secure_context = HTML::is_secure_context(HTML::relevant_principal_settings_object(global));
 )~~~");
 
     auto add_interface = [class_name](SourceGenerator& gen, IDL::Interface const& interface) {
@@ -393,6 +420,11 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global)
         gen.set("interface_name", interface.namespaced_name);
         gen.set("prototype_class", interface.prototype_class);
 
+        if (interface.extended_attributes.contains("SecureContext")) {
+            gen.append(R"~~~(
+    if (is_secure_context) {)~~~");
+        }
+
         gen.append(R"~~~(
     global.define_intrinsic_accessor("@interface_name@"_utf16_fly_string, attr, [](auto& realm) -> JS::Value { return &ensure_web_constructor<@prototype_class@>(realm, "@interface_name@"_fly_string); });)~~~");
 
@@ -417,6 +449,11 @@ void add_@global_object_snake_name@_exposed_interfaces(JS::Object& global)
             gen.append(R"~~~(
     global.define_intrinsic_accessor("@legacy_interface_name@"_utf16_fly_string, attr, [](auto& realm) -> JS::Value { return &ensure_web_constructor<@prototype_class@>(realm, "@legacy_interface_name@"_fly_string); });)~~~");
         }
+
+        if (interface.extended_attributes.contains("SecureContext")) {
+            gen.append(R"~~~(
+    })~~~");
+        }
     };
 
     auto add_namespace = [](SourceGenerator& gen, StringView name, StringView namespace_class) {
diff --git a/Tests/LibWeb/Text/expected/secure-context.txt b/Tests/LibWeb/Text/expected/secure-context.txt
new file mode 100644
index 0000000000..7d007925be
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/secure-context.txt
@@ -0,0 +1,5 @@
+{
+  "SubtleCrypto": false,
+  "Clipboard": false,
+  "CookieChangeEvent": true
+}
diff --git a/Tests/LibWeb/Text/input/secure-context.html b/Tests/LibWeb/Text/input/secure-context.html
new file mode 100644
index 0000000000..60a5da9213
--- /dev/null
+++ b/Tests/LibWeb/Text/input/secure-context.html
@@ -0,0 +1,35 @@
+<!DOCTYPE html>
+<script src="include.js"></script>
+<script>
+    asyncTest(async (done) => {
+        const httpServer = httpTestServer();
+        const url = await httpServer.createEcho("GET", "/secure-context-idl", {
+            status: 200,
+            headers: {
+                "Access-Control-Allow-Origin": "*",
+                "Content-Type": "text/html",
+            },
+            body: `
+                <script>
+                    // HTTP is not a secure context.
+                    internals.setEnvironmentsTopLevelURL('http://ladybird.org');
+
+                    parent.postMessage({
+                        SubtleCrypto: !!crypto?.subtle,
+                        Clipboard: typeof navigator.clipboard === "object",
+                        CookieChangeEvent: typeof CookieChangeEvent === "function",
+                    }, "*");
+                <\/script>`,
+        });
+
+        const frame = document.createElement('iframe');
+        frame.src = url;
+
+        addEventListener("message", (event) => {
+            println(JSON.stringify(event.data, null, 2));
+            done();
+        }, false);
+
+        document.body.appendChild(frame);
+    });
+</script>