The 22-year-old has become the club’s second signing of the summer as manager David Moyes continues to make drastic changes to his squad ahead of the new season. Barry joins on the back of an impressive debut season in La Liga, in which he notched 11 goals and four assists.
Moyes convinced Barry to make the move
Speaking to the club website, the 6ft 5in forward who is set to replace Dominic Calvert-Lewin, expressed how happy he is to join the Toffees and make his dream of playing in the Premier League come true.
"I'm very happy. It's very exciting to be here. I just can't wait to start and I hope to start very quickly.
"Everton is a big club in the Premier League. They have a good history and good players have played here, like Wayne Rooney and Romelu Lukaku. When I was young I liked to watch these players, now I want to do like these players who have gone before.
"I had good conversations with the manager. He told me I have the quality to play in the Premier League. He wants to do good work with me. He wants to help me on my road and I felt the sincerity with him so that's why I chose to come here as well.
"For me, it is a dream to play in the Premier League. I think I proved in my career so far that I can adapt. For example, last season I went to LaLiga, which is a top league, and I think I had a good season for my first season. I'm not scared to play here and do the same."
Barry cannot wait to score in front of Everton's "crazy" fans
The Spanish outfit were determined to get close to the £34M release clause in Barry’s contract but the club has revealed that Barry joins on an undisclosed fee. He spoke more on the passion Everton fans have and how he cannot wait to score in their newly finished stadium next season.
"I think the fans here are, like, crazy people... I like this!" he said. "I like to score for these people. I just want to play here, score and enjoy it with the fans.
"On the pitch I always give 100 per cent, I always want to score, I always want to help the team to win. This is my character. For me, this is my meal, my food. When I score, I'm very happy. I will always give 100 per cent on the pitch and try to score goals.
"The stadium is very big, it's an amazing stadium, and I'm looking forward to seeing the fans in here.
"When the manager came last season, I think he changed a little bit the team and I feel this and the new stadium, I think the Club comes with a new ambition, so I want to play my part in that."
Moyes believes Barry has a lot of potential
Finally, Moyes commented on the deal and revealed that more signings are on the way.
"We are delighted to have brought Thierno to the Club. We see lots of potential and we are hoping for good things from him.
"We will give him plenty of time to settle in and we are looking forward to getting started working with him as soon as possible.
"I'm hoping to make more additions in the coming weeks."