Ukrainian Marta Kostyuk will replace her in the draw, playing Linda Noskova on the opening day on Sunday.
"I am really sad to inform all my fans and supporters that I unfortunately have to withdraw from the WTA Finals this year,” Rybakina said in a statement.
"I’ve had an incredible season, but my body is just not physically ready to compete.
"I’m going to spend some time resting and recovering at home and getting myself ready for the 2027 season."
Rybakina won her second major title of 2026 - and her third overall - at Flushing Meadows two months ago, despite entering the tournament with injury concerns, after hurting her leg at the Cincinnati Open.
She withdrew from the Tokyo quarter-finals last month because of a neck injury.