He played for his father, Dave, at Fort Scott Community College in 1999 before transferring to Seminole (OK) Junior College in 2000, where he was an All-American and the MVP of the Junior College World Series.
He had been drafted by the Florida Marlins in both the 1998 and 1999 amateur drafts, but refused to sign. He was drafted by the Atlanta Braves in 2000 and did sign.
For the start of the 2004 season, the Braves made LaRoche, who had not yet made his major league debut, their starting first baseman. The left-handed LaRoche platooned with 46 year-old veteran Julio Franco and put up a respectable .278 rookie batting average.
LaRoche demonstrated his strong defensive skills at first base, but also his lack of speed on the basepaths.
He again platooned with Franco in 2005. While he did hit 22 home runs, LaRoche had a very streaky season. He hit .385 in his final 17 games of the year, but just .105 in the 19 games that preceded that streak. He batted .500 with a grand slam in the Braves 2005 NLDS Series against the Houston Astros. With the offseason departure of Franco, LaRoche became the Braves sole starter at first base in 2006.
LaRoche was heavily criticized for a lackadaisical error he committed in a game on May 14, 2006. He shuffled to first base so slowly on a routine groundball he had easily fielded, that Washington Nationals baserunner Nick Johnson was able to beat him to the bag. LaRoche had turned his back to the play and was unaware that the runner had sped up. He was already moving towards the dugout when he saw the runner called safe, much to his disbelief. It should have been the third out of the inning, but instead the inning continued with four runs eventually scoring. The normally genteel Atlanta crowd booed LaRoche for the rest of the game and the blunder was replayed repeatedly by local Atlanta media. Manager Bobby Cox even benched LaRoche for some of the next game as punishment. This incident is said to reflect LaRoche's struggles with Attention Deficit Disorder.
However, LaRoche's season turned around after the "Nick Johnson incident." On May 28, 2006, LaRoche contributed two of the Braves' record eight home runs in a remarkable win against the Chicago Cubs. In addition, in a wild game against the San Diego Padres on July 14, 2006, LaRoche hit two more home runs and had five RBIs to help the Braves to a 15-12, 11-inning win. He finished the year with a .285 average, 30 home runs, and 90 RBIs - all career-bests.
The Braves traded LaRoche and minor league outfielder Jamie Romak to the Pittsburgh Pirates on January 17, 2007 for reliever Mike Gonzalez and minor league shortstop Brent Lillibridge.
LaRoche is married to his wife, Jennifer, and they have a daughter, Montana, and a son, Drake. His hobbies include fishing, hunting, and golf.
He is the son of former Major League pitcher Dave LaRoche, and his younger brother, Andy LaRoche, plays for the Dodgers' Triple-A Las Vegas team and is one of the nation's top minor league prospects.