The 24-year-old American was scheduled to defend her Olympic title on Thursday, which she now will not be doing due to the latest withdrawal.
“After further medical evaluation, Simone Biles has withdrawn from the final individual all-around competition. We wholeheartedly support Simone’s decision and applaud her bravery in prioritizing her well-being. Her courage shows, yet again, why she is a role model for so many,” USA Gymnastics said in a statement.
The organization added that she will be evaluated daily to see whether she will take part in the individual event finals next week.
“Jade Carey, who had the ninth highest score in qualifications, will participate in [Biles’s] place in the all-around,” the organization stated.
Carey initially did not qualify because she was the third-ranking American behind Biles and Sunisa Lee. International Gymnastics Federation rules limit countries to two athletes per event in the finals.
The shocking announcement comes after Biles on Tuesday abruptly pulled out of the women’s gymnastics team final, following one rotation and having received a low mark. She said she decided to opt out because she wasn’t mentally ready.
“We have to protect our mind and our body rather than just go out there and do what the world wants us to do,” Biles told reporters on Tuesday.
Team USA gymnastics ultimately won silver. Russia seized the gold while Britain took the bronze.
The Associated Press contributed to this report.