The Japanese world No. 3 was due to face Australia’s Ashleigh Barty later in the day and her place in the tournament will now be taken by alternate Kiki Bertens of the Netherlands.
“I’m disappointed to have to withdraw from the Finals,” Osaka said. “It has been a great event in Shenzhen, and it’s the biggest WTA event of the year. This is not how I wanted to end this tournament or my season.
“I look forward to getting healthy and hope to be back here in Shenzhen next year.”