The French centre-back, who has made 15 appearances for City in the 2017/18 campaign, will now spend the rest of the season with the Toffees.
The move is Mangala’s second loan spell while a City player, after he spent the 2016/17 season with Valencia.
Having represented the La Liga outfit 33 times, he was retained by Pep Guardiola upon his return to the Etihad Stadium.
In total Mangala has made 79 appearances for City since his switch from Porto in August 2014.
Mangala’s debut for the Blues arrived in a 1-1 draw against Chelsea and he went on to clock up 31 appearances in his maiden campaign in Manchester.
Although much of the following season was blighted by injury, he helped Manuel Pellegrini’s side to Capital One Cup success in 2016, featuring in the fourth, quarter-final and semi-final rounds before City defeated Liverpool on penalties at Wembley.
Everyone at Manchester City would like to wish Eliaquim the very best of luck for his time with Everton.