Galatasaray sporting director Bulent Tulun said Mikel has agreed in principle to join them, according to a leading Turkey football website fotomac.
MTNFootball.com reports that the Nigerian international is expected to replace Brazil star Fillipe Melo, who is on his way to either Brazil or Italy.
Chelsea returning boss Jose Mourinho and both clubs are expected to decide on this transfer, said Tulun, who met with other top officials this week on the matter.