The 25-year-old Italian has not played since winning his fifth Grand Slam title at Wimbledon in July. The same injury forced him to miss the Canadian Open, Cincinnati Open and the US Open.
In a statement posted on social media on Friday, Sinner expressed his disappointment at being unable to defend the title he won in Beijing last year.
“I’m very sorry to announce that I won’t be able to play in Beijing this year,” he said. “My knee is not where I would like it to be, and I’m not ready to compete yet, but I will do everything possible to be back on court as soon as I can.
“What I miss the most is, of course, the tournament, the fans and the atmosphere. I’ve had a great time in the past, including winning the title last year, and I’m very disappointed that I cannot defend it this year, but I’m very happy to come back next year.
“So I wish everyone a very good tournament, and I’ll see you all very soon on court again.”
Sinner defeated American Learner Tien in straight sets in the 2025 final to claim his second China Open title, having also won the event in 2023.
His absence removes the top seed from the ATP 500 tournament, which runs from 30 September to 6 October. Attention will now turn to other big names in the draw, including Novak Djokovic.
The 24-time Grand Slam champion is returning to the China Open after an 11-year absence. Djokovic holds a perfect record in Beijing with a tournament-best six titles and will be looking to rebuild momentum after a first-round exit at the US Open that saw him drop to world number 12.
Sinner’s prolonged absence has created a significant gap at the top of the men’s game. The Italian had been in outstanding form before the injury, consolidating his position as the clear world number one. His priority remains a full recovery rather than a premature return that could risk further setbacks.
Fans and the tennis community will now wait for further updates on his rehabilitation as the Asian swing of the ATP calendar continues without the defending champion in Beijing.