Reid began her Grand Slam tennis career in 1963 when she reached the third round of the Australian Championships. In 1966, she reached the semifinals of both the Australian and US Championships (defeating Billie Jean King, in the second round of the latter tournament). In 1967, Reid again reached the semifinals of the Australian Championships and reached the semifinals of the French Championships for the first and only time.
Reid was the women's singles runner-up at the 1970 Australian Open, losing to Margaret Court in the final in straight sets. Reid also was the women's singles runner-up at the US Open in 1972, losing to King after defeating Chris Evert in one semifinal 6–4, 6–2.
In 1972, Reid reached the final of the inaugural WTA Tour Championships, where she lost to Evert 7–5, 6–4.
In January 1977, Reid won her only Grand Slam singles title when she defeated fellow Australian Dianne Fromholtz 7–5, 6–2 in the final of the Australian Open. Reid and Fromholtz were the only top 10 players who played the tournament. The previous week, Reid also defeated Fromholtz in the final of the New South Wales Open, where Reid and Fromholtz again were the only top 10 players who entered. On both the Virginia Slims and the Colgate Grand Prix tours in 1977, Reid qualified for the season-ending tournaments (each limited to the top eight players on the respective tour). And in World Team Tennis, Reid was undefeated in singles against both Martina Navratilova and Virginia Wade, defeating each three times.
Reid capped her last year on the professional tour in 1979 by beating Navratilova for the first time in tournament play. Reid defeated Navratilova in a Family Circle Cup semifinal 6–3, 7–6 before losing to Tracy Austin in the final 7–6, 7–6. Reid also competed in the year-ending WTA Tour Championships (limited to the year's top 8 players).
Reid won the Australian Open women's doubles title twice, outright in 1968 and shared in December 1977. With Wendy Turnbull in 1978, Reid won the women's doubles title at Wimbledon, was the doubles runner-up at the US Open, and won the doubles titles at the Virginia Slims of Seattle, the Virginia Slims of Philadelphia, the US Women's Indoor Championships, and the New South Wales Open.
Reid was a member of the Australian team that won the Federation Cup in 1968. She also helped Australia reach four consecutive Federation Cup finals from 1976 through 1979 on a variety of court surfaces. During that run, she beat several top players, including Rosemary Casals (1976 final on carpet), Wade (1977 semifinal on gras in Eastbourne just weeks before Wade's Wimbledon victory), Austin (1978 final in Melbourne on grass) and Hana Mandlíková (1979 semifinal on clay).
Reid defeated Austin the first three times they played, although Austin won their remaining five career matches. Reid also defeated Mandlikova in both of their career matches.
Reid was a member of the "Houston 9", the breakaway group led by Gladys Heldman in 1971 that formed the nucleus of the women's professional tennis tour.
Reid anchored a World Team Tennis team for each season of its inaugural incarnation (Boston Lobsters 1974–1976 and San Diego Friars 1977–1978).
She married Grover "Raz" Reid, a Boston Lobsters teammate, on 27 April 1975 in Greenville, South Carolina. Raz retired as a player in 1977 and coached Kerry during the remaining three years of her playing career. The Reids then retired to Raz's home state of South Carolina and raised two daughters.
Reid was made a Member of the Order of the British Empire by Queen Elizabeth II in 1979. In 2014, she was inducted into the Australian Tennis Hall of Fame.
SR = the ratio of the number of Grand Slam singles tournaments won to the number played.
Note: The Australian Open was held twice in 1977, in January and December.