From 2000 to 2001, Alexander appeared as Maya Wilkes' husband Darnell during the first season of the UPN sitcom "Girlfriends". He left "Girlfriends" to star as single father Mark "Flex" Washington on the UPN sitcom "One on One", a series he created and produced. For his role on the series, Alexander was nominated for three NAACP Image Awards and two BET Comedy Awards. In 2004, he portrayed Michael Jackson in the VH1 television biopic "", which garnered him another NAACP Image Award nomination. Alexander returned to "One on One" for two more seasons, however, during the last season, his character was written out and reduced to a recurring role when the show's premise was rebooted.