During his playing career, Chavez won six Gold Glove Awards (2001–2006) and a Silver Slugger Award (2002).
Chavez's high school success was such that in the 1996 Major League Baseball draft, he was selected by the Oakland Athletics in the first round as the tenth pick. Chavez eventually chose a professional baseball career over a full scholarship at the University of Southern California (USC), signing with the Athletics on August 27, 1996. His time in the minor leagues was relatively short, lasting just under two seasons. He spent the 1997 season playing for the Visalia Oaks, the Single-A team in the Athletics' farm system. He played 134 games, all at third base, and hit .271 with 18 home runs and 100 RBI. Before the start of the 1998 season, Chavez was promoted to the Double-A Huntsville Stars. After 88 games, he had a batting average of .328, 28 home runs, 86 RBIs, 12 stolen bases, and a triple. His efforts caused him to be promoted to the Edmonton Trappers, where in 47 games he hit 11 home runs and had a .325 batting average. When Edmonton's season finished up on September 8, 1998, he was called up to the major leagues. He finished his minor league career by being named Minor League Player of the Year by Baseball America, as well as earning the J.G. Taylor Spink Award as the Topps/NAPBL Minor League Player of the Year.
He made his major league debut on September 8, 1998, in a game against the Baltimore Orioles, where he came in as a pinch hitter for Mike Blowers and struck out in his only at bat. He finished the 1998 season having played in 16 games, and ending with a .311 batting average, as well as a triple.
Chavez won six consecutive Rawlings Gold Glove Awards from 2001 to 2006. In 2004, the A's signed him to a six-year, $66-million contract extension.
In the 27 games of September and October in 2001, Chavez hit ten home runs with 31 RBIs, a .379 batting average and a .738 slugging percentage resulting in him being named the American League Player of the Month for the only time in his career.
Between 2002-2005, his batting average remained consistent, hitting in the .270-.280 range. His home runs hit remained steady, hitting 29 in 2003 and 2004, and 27 in 2005. However, his offense production dropped in 2006, with his batting average dropping to .241, despite hitting 22 home runs. This slump continued into 2007, hitting .240 and 15 home runs.
Through his first ten years with the A's, Chavez played 1256 games and batted .269. He had 227 home runs and 762 RBIs. Chavez batted .250 and slugged .445 in April and in May combined, but batted .294 and slugged .544 in June, July and August, continuing a constant theme in the Oakland A's organization in that they are a "second half" team.
He started the 2008 season on the disabled list, due to back pain. He was activated from the disabled list on May 29. On July 2, he was placed on the 15-day disabled list again with right shoulder inflammation. On June 14, 2009, Chavez was placed on the disabled list once again due to back pain, this time out for the season.
Chavez became a free agent at the conclusion of the 2010 season when the Oakland A's declined a club option to keep him on the roster for the 2011 season. He had the longest continuous tenure as an Athletic, at 13 years, and second overall total behind Rickey Henderson's 14 years.
On February 4, 2011, Chavez agreed to a minor league contract with the New York Yankees with an invitation to spring training for the 2011 season. The major league team purchased his contract on March 28, 2011.
On May 5, 2011 Chavez broke a bone in his left foot while rounding second base in a game against the Detroit Tigers.
On July 26, 2011 Chavez returned from the disabled list and batted 8th for the Yankees against the Seattle Mariners.
On August 3, 2011, Chavez hit his first home run as a Yankee, a towering two-run shot to right field against the Chicago White Sox.
On February 27, 2012 Chavez re-signed with the Yankees for one season. Chavez is guaranteed $900,000, and can earn an additional $3.05 million in incentives based on plate appearances.
Chavez suffered a minor concussion when diving for a ground ball during a game on May 2, 2012. He left the game and was placed on the 7-day disabled list for concussions. He returned to action on May 11.
Chavez agreed to a one-year contract worth $3 million with the Arizona Diamondbacks for the 2013 season. On June 1, 2013, Chavez was placed on the 15-day DL due to a minor right oblique tear. On December 19, 2013, Chavez re-signed with the Diamondbacks for $3.5 million. Chavez retired on July 30, 2014.
On February 26, 2015, Chavez was hired as a part-time color analyst for Oakland A's telecasts on Comcast SportsNet California. He will team with play-by-play announcer Glen Kuiper to call 20 games during the 2015 season, and will also serve as a pre-game and post-game studio analyst for the channel.
Chavez served as a special assistant to Yankees executives Brian Cashman and Billy Eppler in 2015. When Eppler became the general manager of the Los Angeles Angels of Anaheim after the 2015 season, he hired Chavez as a special assistant.