Saracens have lost two frontline scrum-halves to injury in England international Richard Wigglesworth and former Springbok star Neil de Kock, while Stringer has slipped behind fellow Ireland caps Connor Murray and Thomas O'Leary in Limerick.
Wigglesworth, who impressed for his country at the recent World Cup, is out for the season after undergoing surgery to repair a damaged ACL, while de Kock is currently sidelined until February after fracturing his arm in the opening Heineken Cup win over Benetton Treviso.
"We are fortunate to have a pair of outstanding young scrum-halves in Ben Spencer and Luke Baldwin, but the injuries to Richard Wigglesworth and Neil de Kock have left us exposed in this pivotal position," said Saracens rugby director Mark McCall.
"We are delighted to have secured the services of Peter Stringer, an experienced player of proven quality."
Stringer has made 90 Heineken Cup appearances for Munster since his tournament debut back in the 1998/99 season and featured in five of the Irish giants' six pool games last season, as well as the Amlin Challenge Cup clashes with Brive and Harlequins.
His most famous score came in the 2006 Heineken Cup Final against Biarritz Olympique when his fine individual effort set Munster on their way to a first continental crown in Cardiff.
But the soon-to-be 34-year-old wasn't involved in either of Munster's dramatic pool wins last month as Tony McGahan opted to start with Murray and use O'Leary as a replacement.
"I believe I still have a lot to offer and want to continue to play at the highest level," said Stringer, who has 98 Ireland caps to his name and tasted Heineken Cup success for a second time in 2008.
"In the situation I currently find myself - that is outside the Munster matchday squad - I think this temporary switch to Saracens will serve my ambition best. This offers me a new challenge and I'm grateful to Munster management for their co-operation.
"I am really pleased to join Saracens - it is an ideal opportunity for me to come to a fantastic club. It is a great honour and I am really looking forward to getting involvedr.
"The opportunity to play in the Heineken Cup is something I cannot wait to get involved in and I am very aware of what Saracens have done in the last couple of seasons, what they achieved last year and the quality of players at the club.
"It has been a bit of a whirlwind week and there is a lot of work to do in the meantime but it would be another fantastic occasion for me if I am involved on Saturday at Wembley."
Saracens' next Heineken Cup fixture is a mouth-watering encounter with the Ospreys at Wembley Stadium this Saturday (kick off 6pm).