The 23-year-old, who won her maiden Grand Slam title at the French Open this year, will be making her singles debut in the October 27-November 3 Finals, which offer $14 million in prize money.
"It's been a goal from the very start of the year to qualify for the WTA Finals," Barty, Australia's first women's number one since Evonne Goolagong Cawley in 1976, told the WTA website.
"I'm proud of the work my team and I have put in to get to this point, and I'm honoured to be among the top eight players of the season."
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Barty will be the first Australian to compete at the season-ending tournament since Samantha Stosur in 2012.
The top eight singles players will face off in a round-robin format with the winner taking home the Billie Jean King Trophy.
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