Redgrave grew up near the banks of the River Thames and took up rowing at age 16. He first represented Great Britain at the world junior championships in 1979 and moved to the senior team two years later. He won his first Olympic gold medal at the 1984 Los Angeles Games in the coxed (with coxswain) fours (four-oared shell) rowing event. That same year he resolved to focus on rowing pairs over single sculls and on the winter sport of bobsledding. His winning streak continued at the 1988 Olympic Games in Seoul, South Korea, where he rowed with Andy Holmes to a gold medal in the coxless (without coxswain) pairs event and earned a bronze medal in coxed pairs.

Though never a classical rower, Redgrave generated enormous power from his 6-foot 5-inch (1.96-metre), 225-pound (102-kg) frame and developed into a clever tactician on the water, knowing instinctively when to dominate other crews and when to hold back. His first partnership with Holmes broke up amid some acrimony, but in the Oxford-educated Matthew Pinsent, eight years Redgrave's junior, he found someone who shared his appetite for competition. At the 1992 Games in Barcelona, Spain, Redgrave and Pinsent won gold in the coxless pair event, and they repeated their victory at Atlanta, Georgia, in 1996. After the 1996 Games, Redgrave announced his retirement from international rowing but returned once more to win gold in the coxless fours event at the 2000 Olympics in Sydney, Australia.

In addition to his Olympic success, Redgrave won nine world championship gold medals. Among his other honours were several victories in the Henley Royal Regatta Diamond Sculls, and in 1986 he earned three Commonwealth Games gold medals, winning the single sculls, coxless pairs, and coxed fours. He was knighted in 2001.