Bonds, 49, appeared at the Giants' facility in Scottsdale, Ariz., slimmer than he did when he played. He will work with the hitters.
"It feels really good to get back to the game that I love," Bonds said.
"I don't even know if I'm good at" working with hitters, Bonds said. "I only have seven days, but I welcome younger guys and veterans to pick my brain."
Bonds has a 10-year services contract with the Giants that includes spring training visits.
Bonds previously expressed interest in returning to the team in some instructional capacity. He spent 15 of his 22 major-league seasons with the Giants.
The controversial former outfielder holds the all-time home runs record with 762 and won seven National League MVPs (five with the Giants). Despite that, he has missed out on being inducted into the Hall of Fame because of his alleged connections to performance-enhancing drugs, which he has denied.