The attacker, who can play either on the wing or in an advanced midfield position, has earned 14 caps for Brazil, but none since starting in their shocking 7-1 defeat to Germany in the 2014 World Cup semifinals.
Bernard began his professional career at Atletico Mineiro in 2010 before joining the Ukrainian champions three years later, where he won the Ukrainian Premier League, Ukrainian Super Cup and Ukrainian Cup three times each.
"It is important that the club want to fight for something", Mina told EvertonTV.
The Everton deals come as a frantic end to what has been a superb transfer window for the Toffees, with the club also bringing in Lucas Digne and Richarlison. The Club reserves the right to buy back the player.
Everton officials were in Barcelona on Thursday to put both players through a medical so their moves could go through ahead of the 5pm deadline for the English transfer window. He has made just six appearances during his time in Spain.
Mina only joined Barca in January from Brazilian side Palmeiras.
"I chose Everton because of all the things I had heard about Marco Silva and after speaking to him I was happy with what he said to me", the midfielder said.
Moments later they also confirmed that Portugal worldwide Gomes would join the Premier League side on loan.
Gomes has always been a fringe player at Barcelona, despite signing for a fee of £31m plus €20m in add-ons in 2016, with only 46 appearances made in La Liga since joining from Valencia.