Romo, who will be 32 at the start of next season, was an All-Star in 2013 as the Giants' closer. He had 38 saves in 43 opportunities and struck out 58 batters in 60.1 innings.
Romo lost the closer role midway through the 2014 season. After Romo blew three out of five save opportunities in late June, manager Bruce Bochy installed Santiago Casilla as the closer.
Casilla remained as the closer through the end of the season and recorded four saves in the playoffs.
Romo has spent his entire professional career with the Giants. San Francisco selected him in the 28th round of the 2005 draft, and he debuted in the majors in 2008.
- Dan Gartland