The former France international was a free transfer after his contract at Sunderland was ended by mutual consent at the end of January.
The 34-year-old failed to find the net in his 11 substitute league appearances this season for the Black Cats after arriving at the club at the start of the campaign.
Saha, who has 20 caps for his country, has been brought in as a replacement for German forward Miroslav Klose, who will be out for the next eight weeks with a knee injury.
SUNDERLAND FIXTURES February 2013 Sat 09 15:00 H Arsenal Sat 23 15:00 A West Bromwich Albion March 2013 Sat 02 15:00 H Fulham Sat 09 15:00 A Queens Park Rangers Sun 17 13:30 H Norwich City Sat 30 12:45 H Manchester United April 2013 Sat 06 15:00 A Chelsea Sat 13 13:30 A Newcastle United Sat 20 15:00 H Everton Sat 27 15:00 A Aston Villa May 2013 Sat 04 15:00 H Stoke City Sun 12 15:00 H Southampton Sun 19 16:00 A Tottenham Hotspur
Source: Sunderland-Mad
Source: FOOTYMAD