Terms of the 34-year-old right-hander's deal were not announced, but it is reportedly worth approximately $900,000.
Peralta, who has pitched in 260 Major League games for the Angels, Royals, Rockies and Nationals, went 1-0 with a 2.02 ERA in 39 appearances for Washington last season.
After signing a Minor League contract with the Nationals prior to the 2010 season, Peralta began the year pitching for Triple-A Syracuse, where he saved 20 games while compiling a 2.08 ERA. Peralta joined the Nationals at the end of June, and he held opposing hitters to a .170 average. He proved to be particularly tough on right-handed hitters, as he held them to a .145 mark and did not fare badly against left-handers either, as they hit just .212.
On Monday, manager Joe Maddon spoke of the Rays' offseason project to rebuild the bullpen and sounded confident when he said: "We're not going to be the first ones out there signing somebody, but as this thing starts to fall a little bit and guys start going other places, we have our eyes on some situations how we want to set it up. We'll see how it all works out. But I believe at the end of the day, we're still going to have a good bullpen."
Already this offseason, the Rays have seen Joaquin Benoit and Randy Choate sign multiyear deals with the Tigers and Marlins, respectively. The fates of relievers Grant Balfour, Dan Wheeler, Lance Cormier and Chad Qualls remain to be determined.
J.P. Howell has been re-signed by the Rays, but he isn't likely to begin the season with the team, as he'll be in the final stages of rehab from left shoulder surgery. Andy Sonnanstine and Mike Ekstrom will return, while Jake McGee and Alex Torres appear to be legitimate candidates to join the bullpen, but there is still dialogue within the organization regarding whether the club wants to commit to the pair becoming relievers rather than starters.
Other candidates include right-hander Jonah Bayliss, who has signed a Minor League deal, and left-hander Cesar Cabral, who was selected from Triple-A Pawtucket's roster during the Major League phase of the Rule 5 Draft on Dec. 9.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.