The former Celtic defender will spend the 2015-16 campaign with the Turkish champions and experience Champions League football for the first time.
Galatasaray has secured the signing of Manchester City defender Jason Denayer on a season-long loan deal.
The 20-year-old center back spent last season on loan at Celtic and won the PFA Scotland Young Player of the Year award after forming a successful partnership alongside Virgil van Dijk as Ronny Deila’s men won the Scottish Premiership.
The Belgium international was rewarded by City with a new five-year contract this summer and he went on to spend the full preseason with Manuel Pellegrini’s side.