Garcia, who has been nursing a right thigh problem, beat Romanian Simona Halep in Sunday's China Open final in Beijing to move into the eighth and final place in the WTA Finals standings ahead of Briton Johanna Konta.
Sharapova into Tianjin Open semi-final
It was not immediately clear if Garcia's withdrawal was due to the injury she had been carrying in Beijing.
"Unfortunately @CaroGarcia has had to withdraw from the #tianjinopen due to injury," organisers said on Twitter.
Garcia's China Open triumph gave her a second consecutive title after winning the Wuhan Open crown last month and the 23-year-old is now primed for a first singles appearance at the season-ending tournament in Singapore starting on Oct 22.
As a result of the her withdrawal from Tianjin, wild card Maria Sharapova will take on Romanian Irina-Camelia Begu in the first round.
Sharapova closing on first title since ban after reaching Tianjin quarters
Konta suffers swift defeat to Ostapenko at Italian Open