The fee represents a healthy profit for the Spanish champions, who signed Mina from Palmeiras for €11.8m (£10.6m) only in January and obtained a buy-back option in the deal.
The 23-year-old Mina, who was impressive in defence at this year's World Cup in Russian Federation where he also scored three goals, will rejuvenate an ageing Everton back line while offering a threat from set-pieces at the other end of the pitch.
Everton have signed Portugal global Andre Gomes on a season-long loan from Barcelona.
Speaking about why he wanted to join, the 23-year-old told the club's website that he discussed Everton with fellow teammate Lucas Digne - who played alongside Mina at Camp Nou - before making the switch.
"I have watched the Premier League for a long time".
New Everton defender Yerry Mina says that he is looking forward to the challenge of competing in the Premier League.
Earlier in the day, the Toffees snagged Bernard on a four-year contract, the Brazilian winger being a free agent after leaving Shakhtar Donetsk when his contract elapsed at the end of last season... I have spoken a lot to the coach and I know his passion for Everton and determination to be successful.
The 25-year-old has won 14 caps for Brazil and arrives at Goodison Park before the close of the transfer window.
He said: "I worked hard during my holiday and now I am ready to play and do important things with the Club".
"Bernard is a great player, a player for the Brazilian national team, and I also followed his progress with Atletico Mineiro", Richarlison said on Wednesday.