Silva has been desperate to bolster Everton's defence all summer and had been linked with a number of targets, such as Manchester United's Marcus Rojo and Newcastle's Jamaal Lascelles, but Mina was his top target.
The Spanish champions have a buy-back option in the deal, which comes little over six months since he arrived from Brazilian side Palmeiras.
Mina, who impressed for Colombia at this summer's World Cup, had been pursued hard by the Blues since his exploits in Russian Federation.
"It is important that the club want to fight for something", Mina told EvertonTV.
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Police are investigating after a baby boy died shortly after being pulled from the water near South Street Seaport. Chiropractor Monte Campbell said his wife, Diana Campbell, first noticed the baby.
Everton are also looking to tie up a deal to sign Kurt Zouma on a season-long loan from Chelsea after they agreed a deal with their Premier League rivals.
For the first time, the Premier League deadline was moved forward to the day before the season kicks off when United host Leicester City on Friday.
"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.
Brighton and Hove Albion secured defensive reinforcement in the shape of former Barcelona right-back Martin Montoya, who joins from Valencia on a four-year deal.
'The manager made me feel confident I wanted to play here because of what he's done in the past. But I was also convinced Everton could improve me and that I would be able to show my best as a player here'. Everton agreed a €2.25m (£2.02m) loan fee for the 25-year-old, who now has a minor injury but passed a medical held in Barcelona, and will pay his wages in full for the season.