While in high school, he studied under Teguh Karya and acted in several movies and plays, until he eventually established his own theatre troupe, Teater Koma, in 1977.
Riantiarno was born in Cirebon, State of Pasundan on 6 June 1949, to M. Albertus Sumardi, a railway employee, and Agnes Artini; his twin brother was named Pujo Purnomo.
He then studied at State Senior High School I and II; during this time, he joined the Tunas Tanah Air troupe and read poetry at the local RRI station.
[1] After graduating from high school, Riantiarno left for Jakarta to attend the Indonesian National Theatre Academy [id].
His credits with Teater Populer include Shakespeare's Macbeth, Tennessee Williams' The Glass Menagerie, Karel Čapek's The White Disease, and his own Doa Natal (Christmas Prayer).
[2][3] Finishing his travels, Riantiarno founded Teater Koma on 1 March 1977, with Rumah Kertas (Paper House) being its first production.
[3] Another of his plays, 1988's Sampek Engtay (based on the Chinese legend Butterfly Lovers), ran afoul of the New Order's discriminatory practices.