Branch Warren first competed in 1992 when he won the Amateur Athletic Union (AAU) Teenage Mr. America competition. His first National Physique Committee (NPC) event was the Teenage Nationals, where he won again. His first IFBB event was at the 2004 Night of Champions competitions, where he placed 8th. His first Mr. Olympia was in 2005, where he placed 8th. The following year, in 2006, he competed in his first Arnold Classic for a 2nd place finish. While slipping to 7th place in 2007, he improved to 4th place in 2008 and 3rd in 2009, while winning the title of "Most Muscular". Branch Warren placed 12th in his 2nd Mr. Olympia contest in 2006. Branch Warren also placed 1st at the 2007 New York Pro.