diff --git a/components/script/dom/urlsearchparams.rs b/components/script/dom/urlsearchparams.rs
index ef27b969990..923d8f9e6ad 100644
--- a/components/script/dom/urlsearchparams.rs
+++ b/components/script/dom/urlsearchparams.rs
@@ -91,6 +91,11 @@ impl URLSearchParams {
 }
 
 impl URLSearchParamsMethods for URLSearchParams {
+    // https://url.spec.whatwg.org/#dom-urlsearchparams-size
+    fn Size(&self) -> u32 {
+        self.list.borrow().len() as u32
+    }
+
     // https://url.spec.whatwg.org/#dom-urlsearchparams-append
     fn Append(&self, name: USVString, value: USVString) {
         // Step 1.
diff --git a/components/script/dom/webidls/URLSearchParams.webidl b/components/script/dom/webidls/URLSearchParams.webidl
index 8d1d2a48392..8c053d38582 100644
--- a/components/script/dom/webidls/URLSearchParams.webidl
+++ b/components/script/dom/webidls/URLSearchParams.webidl
@@ -9,6 +9,7 @@
 [Exposed=(Window,Worker)]
 interface URLSearchParams {
   [Throws] constructor(optional (sequence<sequence<USVString>> or record<USVString, USVString> or USVString) init = "");
+  readonly attribute unsigned long size;
   undefined append(USVString name, USVString value);
   undefined delete(USVString name);
   USVString? get(USVString name);
diff --git a/tests/wpt/metadata/url/urlsearchparams-size.any.js.ini b/tests/wpt/metadata/url/urlsearchparams-size.any.js.ini
deleted file mode 100644
index 4d0fec026f1..00000000000
--- a/tests/wpt/metadata/url/urlsearchparams-size.any.js.ini
+++ /dev/null
@@ -1,26 +0,0 @@
-[urlsearchparams-size.any.html]
-  [URLSearchParams's size and deletion]
-    expected: FAIL
-
-  [URLSearchParams's size and addition]
-    expected: FAIL
-
-  [URLSearchParams's size when obtained from a URL]
-    expected: FAIL
-
-  [URLSearchParams's size when obtained from a URL and using .search]
-    expected: FAIL
-
-
-[urlsearchparams-size.any.worker.html]
-  [URLSearchParams's size and deletion]
-    expected: FAIL
-
-  [URLSearchParams's size and addition]
-    expected: FAIL
-
-  [URLSearchParams's size when obtained from a URL]
-    expected: FAIL
-
-  [URLSearchParams's size when obtained from a URL and using .search]
-    expected: FAIL