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