Lewis's 1990 Commonwealth Games gold medals were in the 200-metre freestyle, the 400-metre freestyle, the 200-metre butterfly, 400-metre individual medley and the 4×200-metre freestyle relay. She also won a bronze in the 200-metre individual medley.
At the 1991 World Championships in Perth she won gold in the 200-metre freestyle, silver in the 400-metre freestyle, silver in the 400-metre individual medley, and bronze in the 200-metre butterfly.
For the rest of her career, Lewis focused on the 800-metre freestyle, in which her best Olympic result was a silver medal at the 1992 Summer Olympics and a silver at the 1994 Rome World Championships. She also won a bronze medal in the 400-metre freestyle in Barcelona. At the 2001 World Aquatics Championships, Lewis won a bronze medal in the 5-kilometre open water competition. She had planned to attempt to qualify for the 10-kilometre open water event at the 2004 Summer Olympics, but this event was removed from the competition. She competed at three Olympics.
Lewis is the current host of the Australian version of The Biggest Loser and has been since the 5th season. She started the first swimming centre based inside a major shopping centre within Australia in 2002 at Westfield Carindale in Brisbane. In September 2010, Westfield's redevelopment plans saw Lewis's pool demolished. She now owns a gift and homewares store in Brisbane, Coming Up Roses. In April 2011, Random House published Hayley's first business book, Dream Believe Create. She married her childhood sweetheart, Greg Taylor, in 1997 and they have two sons, Jacob and Kai.
She is also a regular contributor to entertainment and lifestyle website Live4.