The Argentine has signed a five-year deal in a £9.5 million transfer.
The Argentine international has signed in a £9.5million deal, which will come as a surprise to many, with earlier reports having stated the deal was closer to £5.5million.
The 24-year-old has signed a five-year deal with the Toffees according to the club's website, having previously passed a medical but having to wait to complete the deal as complications arose surrounding a work permit.
He is the Blues fifth summer signing, coming after they had previously completed deals for Tom Cleverley, Gerard Deulofeu, Mason Holgate and Leandro Rodriguez.
The completion of the deal will come as a major boost for manager Roberto Martinez, who has been left frustrated this summer as he tries to improve his squad after a disappointing campaign last year.
More importantly though, it will provide him with the extra defensive cover he has sought, having only had Phil Jagielka and John Stones as his senior centre halves for this season following the exits of Antonlin Alcaraz and Sylvain Distin at the end of last season.
Funes Mori arrives at Goodison Park after an impressive season with River Plate in which he managed 10 goals, and secured the Copa Libertadores, the South American version of the Champions League.