The suspect taken into custody is Venissa Maldonado of Fullerton.
Police served a search warrant at approximately 1:45 a.m. early Friday morning in the 400 block of W. Orangethorpe Avenue, not far from where the baby was found.
Maldonado's bail is set at $500,000. She's due in court on Monday.
The baby was found after crying was heard in the bathroom of the Chevron at 944 W. Orangethorpe Ave. on Thursday afternoon.
The child was taken to a hospital and remains in critical but stable condition.
Police also want to remind people that California has a Safely Surrendered Baby Law, which allows parents to safely surrender their newborns at a hospital, fire station or other designated site within 72 hours of birth. The surrender can be done confidentially and without fear of prosecution. To find the closest Safe Surrender location, call (877) BABY-SAF.