The Premier League club also parted company with Ramiro Funes Mori, Wayne Rooeny and Davy Klaassen among others in the summer transfer window.
The La Liga champions confirmed Mina's move for a fee of around £27 million, saying they had an option to buy him back.
New Everton defender Yerry Mina has revealed that he is looking forward to the challenge of competing in the Premier League. Six months later and after a good World Cup, they have moved him on for nearly three times what they paid for him, despite him never quite performing during his short stay.More news: Qeensland best placed to see meteor shower
Manchester United spent the entire summer transfer window scouring for a centre-back who could not just add solidity at the back but also be a leader in defence.
"For me, it was really good to speak to him because I know how good he is and I feel motivated to work with him and to play for Everton, a great club".
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.More news: José Mourinho does not expect any Manchester United deadline-day signings
However, as Barcelona signed three South American players this summer, it became abundantly clear that Mina will become an expendable, with his departure only a matter of time.
Everton have a good squad, and with a new manager in Marco Silva now in charge of the Toffees, the Goodison Park faithful should be excited about the season ahead.
"I spoke to Lucas and he told me all about the Club, which also made me keen to come here".More news: Jose Mourinho aims early dig at 'serial winners' Liverpool and Tottenham