The 31-year-old is getting a two-year, $31 million deal that includes $23 million guaranteed to join a young, up-and-coming squad that also has former Houston Texans teammate DeAndre Hopkins.
Watt made the announcement himself on Twitter and it didn't leak before he did so. Here's his tweet:
The fact that no one had any idea the Cardinals were even on Watt's radar made the reactions to his decision pretty epic. People were legitimately shocked and tweeted as such.
Here are some of the best reactions from Twitter: