The 19-year-old Morocco international defender has signed a four-year deal with the Blues, joining for an undisclosed fee.
Aznou told evertontv: “I'm so happy to be here. I'm so proud to be part of this team.
“The project they gave me is really good. The Premier League is the best league in the world so I'm really excited to start.
“The stadium is really nice. It gives you a good feeling and it's good for our fans to support us. It's perfect for us.
“I just have to say I'm really thankful to be here. I'm really proud so I will give everything in every training session and every game.”
Aznou left Barcelona as a 16 year-old for Bayern and moves to Everton eager to launch his senior career.
Blues boss David Moyes said: “We are pleased to bring Adam to Everton. He’s a young talented player with a lot of potential.
“Left-backs are not easy to get and we’ve brought in a young player who we hope will grow in his time at Everton.”