The closer and the Brewers agreed Thursday to a $13 million, two-year contract, a deal subject to the successful completion of a physical.
"One of the things we focused on was the depth in our bullpen, and bringing back a closer who's very durable put everybody back into a natural spot," Brewers owner Mark Attanasio said. "It actually turns a bullpen which may have been looked at as thin into a bullpen that has some depth when you go through it."
The 33-year-old Rodriguez revived his career last season, when he converted 44 of 49 save chances. Rodriguez went 5-5 with a 3.04 ERA, with 73 strikeouts and 14 home runs allowed in 68 innings.
"We got a lot better," catcher Jonathan Lucroy said. "Frankie has been good for us in the past; he was good for us last year. Hopefully, he can continue to do that this year. We've got some depth now. Hopefully, everybody can stay healthy."
Adding bullpen help, especially an experienced closer, was an offseason priority for general manager Doug Melvin.
With Rodriguez likely to begin the season as closer, right-hander Jonathan Broxton figures to slot into a setup role. He was acquired last year in a late-season trade with Cincinnati.
"There are plenty of important outs in the seventh and eighth innings," Broxton said. "So long as we're winning games, I don't care where I pitch."
Left-hander Will Smith and right-hander Jeremy Jeffress also figure to provide power arms out of the bullpen. Right-handers Jim Henderson, who saved 29 games in 2013, and Tyler Thornburg have recovered from season-ending injuries.
"He allows you to put some of the guys that I was thinking about being maybe in a closing role, it puts them back in a role where I really can match up and they don't have to pitch four, five days in a row," manager Ron Roenicke said.
Originally acquired from the New York Mets during the 2011 All-Star break, Rodriguez accepted arbitration after the season and settled for an $8 million deal. When he couldn't find a deal for 2013, he signed a minor league contract with Milwaukee in April, joined the team in May and pitched well enough to be dealt at the deadline to Baltimore.
He had a $2.25 million base salary in 2013 and earned $50,000 in bonuses, then signed with Milwaukee for $3.25 million last year and earned $600,000 in bonuses.
Attanasio had been in regular contact with Rodriguez's agent, Scott Boras, during the offseason. The 13-year veteran had been seeking a multiyear deal and entertained offers from several other teams, but often has said he feels comfortable in Milwaukee.
"Doug talks about a lot -- and it's important to me, too -- is players who want to be in Milwaukee," Attanasio said. "It's always been clear that he wants to be here."
Rodriguez is in his native Venezuela and won't join the Brewers until he obtains a work visa. The team will have to clear space on the 40-man roster before the deal is finalized.