The switch-hitting Torres likely will serve as the club's fourth outfielder, replacing left-handed-batting Gregor Blanco in left field when San Francisco faces a challenging left-handed starter. Though Torres hit .230 overall for the Mets this year, he batted .286 against left-handers and .195 off right-handers.
Torres accelerated the Giants' drive to a World Series title in 2010 by hitting .268 with 16 home runs, 63 RBIs and 26 steals. He batted .276 that postseason, including .318 in the Fall Classic against Texas.
Torres slumped to .221 in 2011 and was traded to the New York Mets, along with right-hander Ramon Ramirez, for Angel Pagan during last year's Winter Meetings. As the Giants won their second World Series in three years in 2012, Pagan entrenched himself as the club's center fielder and leadoff hitter, duties that Torres formerly performed.
But Torres, 34, was willing to fill any role to return to the Giants.
"I just want to be there," he said. "[Manager Bruce] Bochy knows that I'm going to be ready to play. They know what I'm about."
Torres, who became a free agent when the Mets declined to tender him a contract on Nov. 30, drew interest from a handful of teams.
"No disrespect to them, but I told my agents that I wanted to play for the Giants," said Torres, whose deal is worth a reported $2 million. "My heart was there. The Giants were the team that gave me an opportunity."
Renowned for his ceaseless effort, Torres could think of only one way to demonstrate his gratitude to the Giants for welcoming him back.
"I'm going to work harder than ever," he said.
Chris Haft is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.