Sigurður studied Theology, Greek and Religious History at the University of Iceland from 1948 to 1950. He then moved to the University of Copenhagen to study Theology and Literature, then History and Literature at the University of Athens, and Literature at the University of Stockholm. He got a BA degree from the New School for Social Research in New York in 1955.
For a few years Sigurður worked as a translator for the United Nations, as well as teaching at the City College of New York, and lecturing on Old Icelandic Literature at the New School for Social Research. In 1956 he moved back to Iceland and became a journalist and editor, and later the headmaster of a correspondence school. He has been involved in a considerable number of literary and political societies, and has also worked as a tour guide in the Middle East, Greece, India, Nepal, Japan and Brazil.
Sigurður has written many books, in Icelandic and English, including novels, poems, plays, travel books, memoirs, essay collections and books about the Icelandic horse, as well as translating works from Danish, English, Greek and German.