The 31-year-old Blanco has appeared in at least 140 games in each of the last three seasons for the Giants. He hit .260/.333/.374 with 16 stolen bases last season, playing left field before moving to center in place of the injured Angel Pagan.
Blanco will shift to a backup role with this week's reported signing of Nori Aoki, but provides valuable experience at all three outfield positions and speed off the bench.
He is a .257/.344/.344 career hitter over parts of six Major League seasons with the Braves, Royals and Giants.
Cash Kruth is a reporter for MLB.com. Follow him on Twitter at @cashkruth. This story was not subject to the approval of Major League Baseball or its clubs.