diff --git a/Libraries/LibWeb/HTML/HTMLSlotElement.cpp b/Libraries/LibWeb/HTML/HTMLSlotElement.cpp
index 0d846292fd6..be48da13d9a 100644
--- a/Libraries/LibWeb/HTML/HTMLSlotElement.cpp
+++ b/Libraries/LibWeb/HTML/HTMLSlotElement.cpp
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2020, the SerenityOS developers.
  * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ * Copyright (c) 2025, Shannon Booth <shannon@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -54,8 +55,17 @@ Vector<GC::Root<DOM::Node>> HTMLSlotElement::assigned_nodes(AssignedNodesOptions
         return assigned_nodes;
     }
 
-    // FIXME: 2. Return the result of finding flattened slottables with this.
-    return {};
+    // 2. Return the result of finding flattened slottables with this.
+    // FIXME: Make this a lot less awkward!
+    auto nodes = DOM::find_flattened_slottables(const_cast<HTMLSlotElement&>(*this));
+    Vector<GC::Root<DOM::Node>> assigned_nodes;
+    assigned_nodes.ensure_capacity(nodes.size());
+    for (auto const& node : nodes) {
+        node.visit([&](auto const& slottable) {
+            assigned_nodes.unchecked_append(*slottable);
+        });
+    }
+    return assigned_nodes;
 }
 
 // https://html.spec.whatwg.org/multipage/scripting.html#dom-slot-assignedelements
@@ -73,8 +83,14 @@ Vector<GC::Root<DOM::Element>> HTMLSlotElement::assigned_elements(AssignedNodesO
         return assigned_nodes;
     }
 
-    // FIXME: 2. Return the result of finding flattened slottables with this, filtered to contain only Element nodes.
-    return {};
+    // 2. Return the result of finding flattened slottables with this, filtered to contain only Element nodes.
+    auto result = DOM::find_flattened_slottables(const_cast<HTMLSlotElement&>(*this));
+    Vector<GC::Root<DOM::Element>> assigned_nodes;
+    for (auto const& node : result) {
+        if (auto const* element = node.get_pointer<GC::Ref<DOM::Element>>())
+            assigned_nodes.append(*element);
+    }
+    return assigned_nodes;
 }
 
 // https://html.spec.whatwg.org/multipage/scripting.html#dom-slot-assign
diff --git a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback-in-document.txt b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback-in-document.txt
index 9fed588d4df..2b1f6401e3e 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback-in-document.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback-in-document.txt
@@ -2,6 +2,6 @@ Harness status: OK
 
 Found 2 tests
 
-2 Fail
-Fail	Children of a slot in a document tree should not be counted in flattened assigned nodes.
-Fail	Slot fallback content in shadow tree should be counted in flattened assigned nodes.
\ No newline at end of file
+2 Pass
+Pass	Children of a slot in a document tree should not be counted in flattened assigned nodes.
+Pass	Slot fallback content in shadow tree should be counted in flattened assigned nodes.
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback.txt b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback.txt
index ea2bc3bac9b..17ce8db3450 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-fallback.txt
@@ -2,17 +2,18 @@ Harness status: OK
 
 Found 13 tests
 
-13 Fail
-Fail	Slots fallback: Basic.
-Fail	Slots fallback: Basic, elements only.
-Fail	Slots fallback: Slots in Slots.
-Fail	Slots fallback: Slots in Slots, elements only.
-Fail	Slots fallback: Fallback contents should not be used if a node is assigned.
-Fail	Slots fallback: Slots in Slots: Assigned nodes should be used as fallback contents of another slot
-Fail	Slots fallback: Complex case.
-Fail	Slots fallback: Complex case, elements only.
-Fail	Slots fallback: Mutation. Append fallback contents.
-Fail	Slots fallback: Mutation. Remove fallback contents.
-Fail	Slots fallback: Mutation. Assign a node to a slot so that fallback contens are no longer used.
-Fail	Slots fallback: Mutation. Remove an assigned node from a slot so that fallback contens will be used.
+12 Pass
+1 Fail
+Pass	Slots fallback: Basic.
+Pass	Slots fallback: Basic, elements only.
+Pass	Slots fallback: Slots in Slots.
+Pass	Slots fallback: Slots in Slots, elements only.
+Pass	Slots fallback: Fallback contents should not be used if a node is assigned.
+Pass	Slots fallback: Slots in Slots: Assigned nodes should be used as fallback contents of another slot
+Pass	Slots fallback: Complex case.
+Pass	Slots fallback: Complex case, elements only.
+Pass	Slots fallback: Mutation. Append fallback contents.
+Pass	Slots fallback: Mutation. Remove fallback contents.
+Pass	Slots fallback: Mutation. Assign a node to a slot so that fallback contens are no longer used.
+Pass	Slots fallback: Mutation. Remove an assigned node from a slot so that fallback contens will be used.
 Fail	Slots fallback: Mutation.  Remove a slot which is a fallback content of another slot.
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-outside-shadow-dom.txt b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-outside-shadow-dom.txt
index e79de39d284..4b026276b24 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-outside-shadow-dom.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots-outside-shadow-dom.txt
@@ -2,5 +2,5 @@ Harness status: OK
 
 Found 1 tests
 
-1 Fail
-Fail	Light DOM slot element should be in flattened assignedNodes
\ No newline at end of file
+1 Pass
+Pass	Light DOM slot element should be in flattened assignedNodes
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots.txt b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots.txt
index 499e7f31e2d..a6a77aa42ba 100644
--- a/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots.txt
+++ b/Tests/LibWeb/Text/expected/wpt-import/shadow-dom/slots.txt
@@ -2,8 +2,8 @@ Harness status: OK
 
 Found 26 tests
 
-12 Pass
-14 Fail
+25 Pass
+1 Fail
 Pass	Slots: Basic.
 Pass	Slots: Basic, elements only.
 Pass	Slots: Slots in closed.
@@ -15,18 +15,18 @@ Pass	Slots: Name matching
 Pass	Slots: No direct host child.
 Pass	Slots: Default Slot.
 Pass	Slots: Slot in Slot does not matter in assignment.
-Fail	Slots: Slot is assigned to another slot
-Fail	Slots: Open > Closed.
-Fail	Slots: Closed > Closed.
-Fail	Slots: Closed > Open.
-Fail	Slots: Complex case: Basi line.
-Fail	Slots: Mutation: appendChild.
-Fail	Slots: Mutation: Change slot= attribute 1.
-Fail	Slots: Mutation: Change slot= attribute 2.
-Fail	Slots: Mutation: Change slot= attribute 3.
-Fail	Slots: Mutation: Remove a child.
+Pass	Slots: Slot is assigned to another slot
+Pass	Slots: Open > Closed.
+Pass	Slots: Closed > Closed.
+Pass	Slots: Closed > Open.
+Pass	Slots: Complex case: Basi line.
+Pass	Slots: Mutation: appendChild.
+Pass	Slots: Mutation: Change slot= attribute 1.
+Pass	Slots: Mutation: Change slot= attribute 2.
+Pass	Slots: Mutation: Change slot= attribute 3.
+Pass	Slots: Mutation: Remove a child.
 Pass	Slots: Mutation: Add a slot: after.
-Fail	Slots: Mutation: Add a slot: before.
+Pass	Slots: Mutation: Add a slot: before.
 Fail	Slots: Mutation: Remove a slot.
-Fail	Slots: Mutation: Change slot name= attribute.
-Fail	Slots: Mutation: Change slot slot= attribute.
\ No newline at end of file
+Pass	Slots: Mutation: Change slot name= attribute.
+Pass	Slots: Mutation: Change slot slot= attribute.
\ No newline at end of file