The Toffees left it late on transfer deadline day to finally get a deal over the line for Mangala.
The 26-year-old had fallen out of favour at Manchester City and, following the arrival Aymeric Laporte, Pep Guardiola was prepared to let Mangala leave the club.
And the France international is thrilled to have completed his move to Goodison Park.
“I am thrilled to have the opportunity to play for Everton and I cannot wait to pull on the royal blue jersey for the first time and give my all for the supporters.”
Mangala moved to England in 2014 after making a name for himself with Portuguese giants Porto.
City released a club statement wishing the defender good luck on his move.
“Everyone at Manchester City would like to wish Eliaquim the very best of luck for his time with Everton,” the statement read.