Djokovic, who finished the year as number one for a record seventh time, won the Australian Open, French Open and Wimbledon while he fell short at the Tokyo Olympics and the U.S. Open final in his quest for a rare golden slam.
The Serb was tied with American great Pete Sampras on six wins for the title first awarded in 1978.
Barty, who won her first Wimbledon title this year and a bronze medal at the Olympics in mixed doubles, previously won the award in 2019.
