Ntshona played deposed President Julius Limbani, the subject of a rescue attempt in The Wild Geese (1978). Limbani is based on Moise Tshombe. He also played a similar role in The Dogs of War (1980) as Dr. Okoye, a moderate political figure thrown in jail by the dictator President Kimba of the fictional Republic of Zangaro.
With Fugard and John Kani, Ntshona wrote the 1973 play The Island, in which he and Kani starred in a number of major international productions over the next thirty years. He and Kani were co-winners of the Tony Award for Best Actor in a Play for their performance in both The Island and Sizwe Banzi is Dead, which he also co-wrote.