Rubeš was born in Volyně, Czechoslovakia, to Ružena (née Kellnerová) and Jan Rubeš. Not long after World War II, he graduated from the Prague Conservatoire and joined the Prague Opera House as a bass singer. In 1948, he won first prize at the Geneva International Music Festival, and emigrated to Canada at the end of the year to pursue a career in a wider sphere. Beginning as a singer with the Canadian Opera Company, he subsequently directed and became Director of touring, before switching to radio and television, where he became known as an actor and presenter well known in Canada. He is noted for his portrayal of Amish patriarch Eli Lapp in Peter Weir's major-market film Witness and Jan in D2: The Mighty Ducks.