diff --git a/.changeset/hip-eels-speak.md b/.changeset/hip-eels-speak.md
new file mode 100644
index 00000000..51459e2f
--- /dev/null
+++ b/.changeset/hip-eels-speak.md
@@ -0,0 +1,7 @@
+---
+'@tanstack/lit-virtual': patch
+---
+
+fix(lit-virtual): create Virtualizer instance before hostConnected
+
+When creating an instance of the reactive controller in `connectedCallback`, calling `addController` will synchronously call `hostConnected` on the controller. This means that `this.virtualizer` will still be `undefined`.
diff --git a/packages/lit-virtual/src/index.ts b/packages/lit-virtual/src/index.ts
index 7a00af05..75b3755a 100644
--- a/packages/lit-virtual/src/index.ts
+++ b/packages/lit-virtual/src/index.ts
@@ -25,8 +25,6 @@ class VirtualizerControllerBase<
     host: ReactiveControllerHost,
     options: VirtualizerOptions<TScrollElement, TItemElement>,
   ) {
-    ;(this.host = host).addController(this)
-
     const resolvedOptions: VirtualizerOptions<TScrollElement, TItemElement> = {
       ...options,
       onChange: (instance, sync) => {
@@ -35,13 +33,15 @@ class VirtualizerControllerBase<
       },
     }
     this.virtualizer = new Virtualizer(resolvedOptions)
+
+    ;(this.host = host).addController(this)
   }
 
   public getVirtualizer() {
     return this.virtualizer
   }
 
-  async hostConnected() {
+  hostConnected() {
     this.cleanup = this.virtualizer._didMount()
   }