diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.cpp b/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.cpp
index 2fea5861a9c..107d8073596 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.cpp
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.cpp
@@ -6,7 +6,9 @@
 
 #include <LibWeb/DOM/HTMLCollection.h>
 #include <LibWeb/HTML/HTMLTableCellElement.h>
+#include <LibWeb/HTML/HTMLTableElement.h>
 #include <LibWeb/HTML/HTMLTableRowElement.h>
+#include <LibWeb/HTML/HTMLTableSectionElement.h>
 
 namespace Web::HTML {
 
@@ -30,4 +32,55 @@ NonnullRefPtr<DOM::HTMLCollection> HTMLTableRowElement::cells() const
     });
 }
 
+// https://html.spec.whatwg.org/multipage/tables.html#dom-tr-rowindex
+int HTMLTableRowElement::row_index() const
+{
+    // The rowIndex attribute must, if this element has a parent table element,
+    // or a parent tbody, thead, or tfoot element and a grandparent table element,
+    // return the index of this tr element in that table element's rows collection.
+    // If there is no such table element, then the attribute must return −1.
+    auto rows_collection = [&]() -> RefPtr<DOM::HTMLCollection> {
+        if (!parent())
+            return nullptr;
+        if (is<HTMLTableElement>(*parent()))
+            return const_cast<HTMLTableElement&>(static_cast<HTMLTableElement const&>(*parent())).rows();
+        if (is<HTMLTableSectionElement>(*parent()) && parent()->parent() && is<HTMLTableElement>(*parent()->parent()))
+            return const_cast<HTMLTableElement&>(static_cast<HTMLTableElement const&>(*parent()->parent())).rows();
+        return nullptr;
+    }();
+    if (!rows_collection)
+        return -1;
+    auto rows = rows_collection->collect_matching_elements();
+    for (size_t i = 0; i < rows.size(); ++i) {
+        if (rows[i].ptr() == this)
+            return i;
+    }
+    return -1;
+}
+
+int HTMLTableRowElement::section_row_index() const
+{
+    // The sectionRowIndex attribute must, if this element has a parent table, tbody, thead, or tfoot element,
+    // return the index of the tr element in the parent element's rows collection
+    // (for tables, that's HTMLTableElement's rows collection; for table sections, that's HTMLTableSectionElement's rows collection).
+    // If there is no such parent element, then the attribute must return −1.
+    auto rows_collection = [&]() -> RefPtr<DOM::HTMLCollection> {
+        if (!parent())
+            return nullptr;
+        if (is<HTMLTableElement>(*parent()))
+            return const_cast<HTMLTableElement&>(static_cast<HTMLTableElement const&>(*parent())).rows();
+        if (is<HTMLTableSectionElement>(*parent()))
+            return static_cast<HTMLTableSectionElement const&>(*parent()).rows();
+        return nullptr;
+    }();
+    if (!rows_collection)
+        return -1;
+    auto rows = rows_collection->collect_matching_elements();
+    for (size_t i = 0; i < rows.size(); ++i) {
+        if (rows[i].ptr() == this)
+            return i;
+    }
+    return -1;
+}
+
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.h b/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.h
index 1a85e95da40..065244ec7a0 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.h
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.h
@@ -18,6 +18,9 @@ public:
     virtual ~HTMLTableRowElement() override;
 
     NonnullRefPtr<DOM::HTMLCollection> cells() const;
+
+    int row_index() const;
+    int section_row_index() const;
 };
 
 }
diff --git a/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.idl b/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.idl
index 8ddaa33eb30..29d21d4f994 100644
--- a/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.idl
+++ b/Userland/Libraries/LibWeb/HTML/HTMLTableRowElement.idl
@@ -10,6 +10,9 @@ interface HTMLTableRowElement : HTMLElement {
 
     [LegacyNullToEmptyString, Reflect=bgcolor] attribute DOMString bgColor;
 
+    readonly attribute long rowIndex;
+    readonly attribute long sectionRowIndex;
+
     [SameObject] readonly attribute HTMLCollection cells;
 
 };