He has signed a five-year contract and joins Lucas Digne, the left back who also moved from the Nou Camp this summer.
Meanwhile Merseyside rivals Liverpool have sent injury plagued striker Danny Ings on loan to Southampton.
Everton have announced that Mina will be No 13 while Andre Gomes will be No 8.
Everton have surely enjoyed the best deadline day of any Premier League club, with three deals all going through in the final moments of the window. His form for them was so good he has been awarded 13 caps for Brazil, although he was not part of their squad that went to the World Cup in Russian Federation this summer.
Woods has sights on 9th title at 'special' Firestone event
The only downside to having a stacked field is that it makes picking players that I think will win, extremely hard . But before I become too emotional, let's jump into the course.
And speaking about his desires for his new side, Mina revealed he has sights set high.
'The manager made me feel confident I wanted to play here because of what he's done in the past.
Everton will open their 2018-19 Premier League campaign against Wolverhampton Wanderers on Saturday afternoon.
Mina's stock is high after he caught the eye during the World Cup - he scored a last minute equaliser against England in the last 16 tie, one of three goals he netted in Russian Federation - and he revealed the lure of the Premier League was impossible resist.
However he is keen to quell any doubts over whether he can make an instant impact due to fitness.
I worked hard during my holiday and now I am ready to play and do important things with the Club.