Steyrer was born on June 3, 1920 in the city of Linz. Steyrer studied medicine in the cities of Vienna and Prague before opening up his own practice in dermatology. His medical background allowed him to serve as the health and environment minister of Austria.
Steyrer was one of the leaders of the Social Democratic Party of Austria.
Steyrer died in Vienna, Austria, on July 16, 2007, after a brief illness. His death was initially reported by the Austria Press Agency and the ORF. Coincidentally, Kurt Waldheim, Steyrer's 1986 presidentially opponent, died less a month before Steyrer in June 2007.