Jason Giambi says he's retiring after 20 major league seasons.
Giambi, who played sparingly over the past six years, announced his decision in a statement to the New York Daily News on Monday.
The former American League MVP appeared in 2,260 games with four teams, most notably the Oakland Athletics and New York Yankees.
One of the preeminent sluggers of his era, Giambi apologized on at least two occasions for taking steroids during his career.
"Ever since I was five years old, all I ever wanted to be was a Major League Baseball player," Giambi said in a statement in which he thanked his family, friends, teammates, owners and fans. "The Oakland A's, New York Yankees, Colorado Rockies and Cleveland Indians were a big part of helping that dream come true."
Giambi, 44, spent the past two seasons with the Indians, making 286 plate appearances in just 97 games. In his last game Sept. 27 against Tampa Bay, he drew a walk in his second-to-last plate appearance and struck out in his final at-bat.
He was the active leader in walks with 1,366 and near the top of the list in strikeouts at 1,572. But he was also fifth on the active list in home runs with 440 and fifth in RBI with 1,441.
At his peak, Giambi was among the most feared sluggers in baseball. Between 1996 and 2008, he averaged 30 homers and 96 RBI and batted .287 with a .410 on-base percentage in 1,796 games.
He was voted the AL MVP in 2000 after hitting .333 with a .476 on-base percentage, 43 homers and 137 RBI for Oakland.
The following season, Giambi set career highs with a .342 batting average and .477 on-base percentage for the A's and finished second in the MVP voting to Ichiro Suzuki.
He was a five-time All-Star and won a memorable 2002 Home Run Derby against Sammy Sosa, but never captured a World Series title. He played for the Yankees from 2002-08, leaving a season before they won it all.
Between 2000 and 2001, Giambi and his brother Jason both played for the A's, which Giambi said Monday were "two of my favorite years of my career."
In December 2004, the San Francisco Chronicle reported that the Giambi brothers admitted to a federal grand jury during the BALCO steroid case that they had taken performance-enhancing drugs during their careers.
According to the report, Jason Giambi testified that he injected himself with human growth hormone during the 2003 season and had started using steroids at least two years earlier.
He apologized twice for his steroid use, once before the 2005 season when he said he "let down the fans" and again in a 2007 interview with USA Today, when he said he was "wrong for doing that stuff" and said Major League Baseball should apologize for its widespread problem with PEDs.