The Brazil striker, who joined City from CSKA Moscow in July 2008 for a fee of around 18million, had been on loan at Everton since August, but was earlier this month reprimanded by manager David Moyes for a breach of club discipline.
Jo, 22, whose full name is Joao Alves de Assis Silva, now appears set to join former Toffees team-mate Lucas Neill in Istanbul.
A statement on Galatasaray's official website read: "Our club have agreed to sign Brazilian Joao Alves de Assis Silva on loan until the end of the season from English Premier League team Manchester City. Joao Alves de Assis Silva is welcome and we wish him success in the yellow and red jersey."
Meanwhile, City manager Roberto Mancini is reportedly interested in signing midfield duo Fernando Gago and Mathieu Flamini before the transfer window closes. The Italian hopes Real Madrid's Gago and AC Milan's Flamini can follow Patrick Vieira, who joined the Eastlands outfit for the remainder of the season from Inter Milan.
"I need players," Mancini was quoted as saying in Gazzetta dello Sport. "Perhaps Real Madrid will give me Gago, maybe Milan (will give me] Flamini..."