Reynolds competed at multiple Olympics, medaling in 1988 and 1992. In 1996 he came in eighth. Afterwards he formed a new partnership with crewman Magnus Liljedahl, and they went on to win a string of championships, culminating with a gold medal at the 2000 Olympics.
Reynolds sailed for San Diego State University, where he received a BS. As a sophomore, Mark was All American on the San Diego State University sailing team in 1974. Mark led the team to a 2nd place finish both in 1974 and 1975 in the North American Dinghy Championships. He also holds an honorary doctorate from Piedmont College.
He owns a sail making company. He made the sails for almost all of his Star class competitors.