Upon reaching the majors in 1999, Singleton hit .300 with 17 home runs and 74 RBI, but his power numbers dropped precipitously each season thereafter. A highlight of his 1999 season was on July 6, when he hit for the cycle becoming the first White Sox player to hit for the cycle in 15 years. On January 29, 2002, he was traded by the White Sox to the Baltimore Orioles for Willie Harris.
Singleton had signed to play with the Pittsburgh Pirates in 2004, but his contract was voided after he failed a physical exam. The team cited a pre-existing ear condition, which had initially been diagnosed as a simple infection, but ultimately proved to be something more serious.[1] On January 21, 2005, he signed with the Tampa Bay Devil Rays, but was released on July 4 after just 59 at-bats.
Paired with play-by-play man and former major league pitcher Ed Farmer, Singleton was the color commentator on Chicago White Sox radio broadcasts for the 2006 and 2007 seasons. However, on March 4, 2008, it was announced that he would be leaving that position to take on an analyst role with the ESPN television program Baseball Tonight. He was replaced by former Chicago Cubs television broadcaster Steve Stone. Singleton also became the lead game analyst for ESPN Radio's baseball coverage in 2011, teaming with play-by-play announcer Jon Sciambi to call Sunday Night Baseball as well as All-Star Game and postseason broadcasts for the network.