With Mike Sherry on the long-term injury list following a recent shoulder surgery the 32-year-old Argentinian has been recruited on a short-term contract.
Guinazu has just completed two seasons at Premiership outfit Bath Rugby and he has previously played for French clubs Biarritz and Toulouse and Super Rugby side the Stormers.
The Mendoza-born international has 36 caps for his country and featured for Argentina in the 2013 Rugby Championship campaign.
Commenting on the signing Head Coach Anthony Foley said, "We need to hit the ground running this season and to do this we need to have a full complement of players available to us.
We have short-term setbacks with Niall Scannell rehabbing from wrist injury and Damien Varley managing a foot injury, but with Sherry ruled out until next year it is great that we can call on the services of an experienced versatile player such as Eusebio. His availability will certainly help us get through the opening period of the season."
In other squad news Cian Bohane will undergo a scan tomorrow after sustaining a knee injury on Friday night in Munster's victory against London Irish at the Waterford RSC.
Name: Eusebio Guinazu
Date of birth: 15th Jan 1982
Birthplace: Mendoza, Argentina
Height: 1.8m (5' 11")
Weight: 114kg (17st 13lb)
Munster open their Guinness PRO12 campaign on Friday night in Thomond Park against Edinburgh Rugby at 7.35pm. Tickets are on sale for this game online here, from the Munster Rugby ticket offices in Musgrave Park and Thomond Park, or by calling 0818 719300.