Her sister Venus Williams and world number four Sofia Kenin will not participate either.
Kenin is also plagued with injury concerns.
"I am rehabilitating in the hope of being able to play the US Open later this month.
I feel that another week of rehab is necessary ", she says.
There was no reason why Venus Williams chooses to withdraw.
Novak Djokovic and Roger Federer have previously resigned from the men's side.
The tournament in Cincinnati is one of the pre-tournaments for the US Open, which begins on August 30.