Australia's Ashleigh Barty poses with a trophy as she celebrates after winning the final against Ukraine's Elina Svitolina. Photo: Aly Song/Reuters

SHENZHEN – Ashleigh Barty finished the season in style by beating defending champion Elina Svitolina 6-4 6-3 to add the WTA Finals title to her end-of-season world number one ranking on Sunday.

Barty, who became the first Australian to top the WTA rankings at the end of the year since they were introduced in 1975, capped a stellar season in Shenzhen having also won the French Open at Roland Garros in June.

Barty became the first Australian to win the WTA Finals since Evonne Goolagong Cawley claimed her second title in 1976.

"It's been the most incredible year for me," said Barty, who pocketed a record $4.42 million for her victory in Shenzhen, where the tournament was being held for the first time as part of a 10-year residency.

"It's been an incredible new era in women's tennis and to play in front of this spectacular crowd has been amazing."