The Braves took to Twitter to announce the deal, which includes a club option for 2017.
The 38-year-old right-hander will fill a setup role for closer Craig Kimbrel. He will help replace Jordan Walden, who was traded with right fielder Jason Heyward to the Cardinals in the offseason deal that sent starting pitcher Shelby Miller to Atlanta.
Grilli was an All-Star closer for the Pirates in 2013, when he had 33 saves. He lost his stopper job before he was traded to the Angels on June 27, 2014. He finished with a combined 12 saves and 4.00 ERA last season.
Information from The Associated Press was used in this report.