Atlanta announced the deal Friday. The NL East champions have a club option on the contract for 2021 at $3.5 million.
The 37-year-old O’Day appeared in just eight games for the Braves last season due to a right forearm strain. He allowed one earned run in 5 1/3 innings in the regular season, then pitched two scoreless innings in the playoffs.
The sidearmer, who graduated from Florida in 2006, has pitched in 12 big league seasons and was an All-Star with Baltimore in 2015. He also missed much of the 2018 season because of injuries.