Guillaume's active TV schedule has limited his film appearances, which began with a role in the blaxploitation flick "SuperFly TNT" (1973). "Lean on Me" (1989) offered the actor one of his best film roles, as the superintendent of schools trying to give support to maverick high school principal Joe Clark (Morgan Freeman). Guillaume was not even seen in his biggest hit, though, voicing the mystical baboon Rafiki in Disney's animated blockbuster "The Lion King" (1994).
With his second wife Donna Brown Guillaume, he executive produced and co-starred in "You Must Remember This", a 1992 PBS "Wonderworks" entry. Between 1994 and 1997, the Guillaumes also produced "Happily Ever After" (HBO), a series of ethnically diverse animated fairy tales, for which he also served as narrator.