After attending Fisk University, his professional acting debut was on the stage, in New York Shakespeare Festival's 1965 off-Broadway production of Troilus and Cressida.
[5] A dozen years later, Jackson returned to Broadway for the premiere of Ma Rainey's Black Bottom, which ran for 276 performances and was chosen "Best Play" by the New York Drama Critics Circle.
[6] In 1991, Jackson was part of the cast for the Broadway premiere of Mule Bone, an unfinished play written by Langston Hughes and Zora Neale Hurston.
[5] The production, mounted for the first time sixty years after it was written, received a negative review by Frank Rich, who said the "three principal performers ... are at best likably amateurish, [though] their efforts are balanced by the assured center-stage turns of such old pros as Leonard Jackson, as a fuming man of the cloth, and Theresa Merritt.
[8] He has also been featured in episodes of dramas such as Law & Order, Homicide: Life on the Street, and Spenser: For Hire, and comedies such as Amen, The Cosby Show, and The Jeffersons.