Baseball Commissioner Bud Selig, in a letter to Giambi, cited the player's cooperation with a steroid-use investigation led by former U.S. Sen. George Mitchell, D-Maine, and his off-field charitable activities in explaining why no other action would be taken.
"Jason was frank and candid with Senator Mitchell," Selig's letter said. "That and his impressive charitable endeavors convinced me it was unnecessary to take further action."
Giambi testified in before a grand just in the BALCO steroids investigation. The San Francisco Chronicle reported that Giambi testified he had used steroids and human growth hormone.
Giambi was reportedly close to be being suspended by Selig earlier this season when he made a vague admission to using performance-enhancing substances.
In May, Giambi told USA Today: "I was wrong for doing that stuff. What we should have done a long time ago was stand up -- players, ownership, everybody -- and said, 'We made a mistake.'"