The Ghana international winger moved to the Toffees on a season-long loan deal after being deemed surplus to requirements by Blues manager Jose Mourinho.
The 22-year-old joined Chelsea on a five-year contract in the summer of 2013 from Portuguese club Porto, but was immediately loaned out to Eredivisie outfit Vitesse.
Atsu had a good time in the Netherlands in the 2013-14 campaign and will now showcase his talent for Everton in the Premier League.
“After the World Cup, when I came back to Chelsea they told me of Everton’s interest,” the youngster said, quoted by the Liverpool Echo.
“I told them Everton were a great club and I would prefer to play for them. I think Everton is a great club with a great manager and they try to play football, which is very important for me.
“When I was training with Chelsea, a lot of the players told me Everton is a great club.
“I have been here a week now and I am so happy with the players, with everyone. I have had warm wishes from the fans on social networks as well, so I am very happy.
“I had a lot of messages and a lot of new followers who are Everton fans, which is great.”