King became the oldest WTA player to win a singles tournament when she won the Edgbaston Cup grass court tournament in Birmingham at 39 years, 7 months and 23 days after a straight-sets victory in the final against Alycia Moulton. Her tally of 20 Wimbledon titles remained when partnered with Steve Denton and the no.1 seeds in the Mixed Doubles, they lost 6–7(5–7), 7–6(7–5), 7–5 to John Lloyd & Wendy Turnbull in the final, King being the only player to drop her service in the final game. At her final appearance at the US Open later in 1983, King didn't play singles, but partnered Sharon Walsh in the Women's Doubles, reaching the semi-finals and Trey Waltke in the Mixed Doubles, losing in the second round. The final official singles match of King's career was a second round loss to Catherine Tanvier at the 1983 Australian Open.