The Super Lig outfit had announced a deal had been agreed on Wednesday, and the 26-year-old has now completed his medical and agreed personal terms.
He leaves a Spartak Moscow side that currently sit top of the Russian Premier League after four games, in no short part down to Emenike’s three goals.
Emenike previously signed for Fenerbahce in July 2011 but in the same month was sold to Spartak after facing charges of match fixing.
He was later acquitted of all charges and returns to Turkey after also featuring for Karabukspor.
Emenike has 15 international caps and has contributed six goals to the Nigeria national team.
Fenerbahce could hand him his debut in the club’s Super Lig opener away to Konyaspor on Saturday.