The Greek international becomes the Black Cats second transfer of deadline day following the signing of Wayne Bridge on-loan from Manchester City.
Wearsiders boss Martin O’Neill is delighted with the capture of the former Liverpool man and believes his strength and experience will help the club in the remaining months of the season.
He told the club’s official website: "Sotirios offers a real physical presence, coupled with a wealth of experience, which will be an undoubted benefit to us in the next few months.
"I'm delighted to welcome him to the club and I'm sure he is looking forward to the challenge of returning to the Premier League."
Kyrgiakos moved to the Bundesliga side last summer after spending two years in the Premier League with the Reds, featuring 49 times in all competitions.
However following his transfer to Germany he has struggled to make an impact and registered just seven appearances in his first six months at the club.
The 32-year old has also played for Panathinaikos, AEK Athens, Rangers, Agios Nikolaos and Eintracht Frankfurt during his career, and has also represented his country 61 times, playing for Greece in Euro 2008 and the 2010 World Cup.