Kenneth Page was born and raised in St. Louis, Missouri. He was raised Catholic by his mother, Gloria and his step-father, Garvin Gilstrap. He attended St. Bridget of Erin and St. Nicholas elementary schools. While attending St. Nicholas, he was inspired by a teacher and an older cousin to pursue theater. He subsequently graduated from Bishop DuBourg High School in 1973. From there he attended Fontbonne College in Clayton, Missouri on a full scholarship and majored in theater.
Page began his career in the chorus of The Muny outdoor theater in St. Louis. After making his Broadway debut in The Wiz, Page played Nicely-Nicely Johnson in the all-black revival of Guys and Dolls (Theatre World Award). He was then featured in the original cast of the Fats Waller musical revue, Ain't Misbehavin' (Drama Desk Award), a role he reprised in the 1982 television broadcast. He also returned to the show in its 1988 Broadway revival. In 1982, he played Old Deuteronomy in Cats, returning to the part in the 1998 video release. He also has the distinction of playing God twice: in Randy Newman's Faust at La Jolla Playhouse and Goodman Theatre and in Stephen Schwartz's Children of Eden (West End). Page frequently acts in shows at The Muny, with appearances including Jesus Christ Superstar, Aida, The Wizard of Oz, Les Misérables, My One and Only, and Little Shop of Horrors.
Besides The Nightmare Before Christmas, Page's major film credits include All Dogs Go to Heaven and Torch Song Trilogy, as well as Dreamgirls. His TV credits include guest roles on shows such as Charmed and Touched by an Angel, as well as various movies and specials.