The clubs agreed a permanent deal for Mina worth £27.2m (€30.25m) rising to £28.5m (€31.75m), while Andre Gomes joins on a season-long loan.
Barca have inserted a buy-back option for the Colombian global, who caught the eye after a series of impressive performances at the Russia World Cup.
"I'm delighted to sign for this fantastic club - it's a good day for me", said Gomes to Everton's in-house TV channel. "This is why I am here".
The new Premier League season starts on Friday. When I found out about this opportunity and what the manager wanted out of me I was happy. I have spoken a lot to the coach and I know his passion for Everton and determination to be successful.
"I spoke to Lucas and he told me all about the club, which also made me keen to come here".
Everton and Fulham stole the show on the Premier League's transfer deadline day, as both clubs welcomed several eye-catching signings.
Barcelona confirmed defender Yerry Mina has signed for Everton.
Mina had always been linked with a move away from Barcelona this summer with the club's purchases of non-EU players in Malcom, Arthur and Arturo Vidal filling their quote per La Liga's rules.
Barcelona have been trying to offload the duo all summer and it seems they will be able to succeed by the transfer window slams shut in England at 5pm. He has made just six appearances during his time in Spain.
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.
The 25-year-old began his career at Benfica, with his career highlight being a European Championship win with Portugal in 2016.