Selected by the Kansas City Royals in the 21st round of the 1994 Major League Baseball draft out of Manatee Community College, Carter spent 6 years in the Royals minor league system, including losing the entire 1997 season due to injury, before making his major league debut with the Royals on September 15, 1999. Carter did not play in the majors in 2000 and became a free agent at the end of the season. He did not play at all in 2001 and signed with the Tampa Bay Devil Rays on January 11, 2002. Carter had a career year in 2003; Carter became the Devil Rays closer and was elected to the All-Star Game as a reserve, but did not play. During the 2003 season, he went 7-5 with a 4.33 ERA. In 2004, Carter had a 3.47 ERA in 56 games, and a 4.89 ERA in 39 games in 2005.