If you are searching for Wrath of the Lamb specifically for its content (items, bosses, difficulty), you should know that The Binding of Isaac: Rebirth includes all the content of Wrath of the Lamb plus vastly more. However, Rebirth does not run in a browser and is not "unblocked" easily.

That said, Rebirth is available on mobile (iOS/Android). If your school allows phones, you have the full Wrath of the Lamb experience in your pocket, completely unblockable.

Here lies the complexity. The original Flash version of Wrath of the Lamb is no longer officially supported.

Therefore, most sites claiming to offer "The Binding of Isaac: Wrath of the Lamb unblocked" are often:

If you are determined to play the classic Wrath of the Lamb on a restricted PC, follow this checklist: