Despite disclosing the transfer fee, Barça did not reveal at what price the buy-back clause is set, but a report from Marca has claimed that it is €60m (£53.9m).
Having only made the move to Europe in January after joining Barça from Brazilian club Palmeiras and playing relatively little football in Spain, Mina is largely unknown to English audiences but for a dramatic late goal he scored against the Three Lions at the World Cup.
Upon joining Everton, Mina told evertontv, “It is important that the club want to fight for something. This is why I am here.
“I have watched the Premier League for a long time. It is the best league in the world. This is a great opportunity for me and I am looking forward to competing here.
“I know about Everton’s players and I look forward to being able to play with my new team. I have spoken a lot to the coach and I know his passion for Everton and determination to be successful. I am also determined to do my best for Everton.”
Mina wasn’t alone in making the switch from Camp Nou to Goodison Park this week, with Barça midfielder Andre Gomes also joining Everton after agreeing a loan move. Meanwhile, Lucas Digne left Barça to sign for Everton earlier in the summer.