Maribel Mejia, 32, of San Martin, surrendered to Morgan Hill police on Monday on a $120,000 warrant. She told investigators she was tired of being on the run, police said.
Mejia was booked into Santa Clara County Jail and remains in custody on $100,000 bail.
A second suspect in the case, Enrique Rocha, remains at large, along with his dark blue 1988 Toyota Camry. The car has a California license plate number of 2HJD721, and both of its rear windows are covered with what may be black duct tape, police said.
Mejia and Rocha were seen walking out of the Reach Out food bank at St. Catherine's Church in Morgan Hill the afternoon of May 31 as the infant's mother was walking in, police said.
The mother, Maribel Corona, had left her baby in her white Infiniti Q45 with the keys in the ignition as she briefly ducked into the food bank, police said. When she came out, the car and her daughter were gone.
Several hours later, the car was found by a hiker at Toro Park near Salinas. The baby was safe inside and was reunited with her mother.
Investigators believe Mejia and Rocha stole the car, according to Morgan Hill police.
Corona's purse was in the car when it was taken, and her credit card was used at a Walmart and a gas station in Los Banos on June 1, police said.
Surveillance video from several locations where the card was used show Mejia using the credit card with Rocha and Mejia's 4-year-old son, police said.
Mejia was arraigned in Santa Clara County Superior Court on Wednesday on felony charges of kidnapping, child endangerment, theft or unauthorized use of a vehicle, and buying, receiving, concealing or withholding stolen property, district attorney's office spokeswoman Lisa McCrary said.
She will plead to those charges on July 26 in Morgan Hill.
Police believe Rocha may be in Los Banos, Stockton or San Jose. Mejia said she spent most of her timing hiding in those cities, and Rocha is known to have contacts in those areas, police.
Anyone with information on Rocha's whereabouts is asked to call Morgan Hill police Detective Guerrero at (408) 779-2101.