The deal will keep the Rangers captain at Ibrox until 2015.
The 34-year-old has scored 14 goals this season after being handed a striking role and the captaincy at the beginning of Rangers' Irn-Bru-Third Division campaign.
The former Motherwell player joined Rangers from Wigan in July 2007 and has played in defence, midfield and attack.
His previous contract expired at the end of this season and his new deal takes him to his 37th birthday.
If Rangers make their way through the current Scottish Football League structure, the final season of his contract could be in the Irn-Bru First Division.