Dwayne Jackson, 25, was charged in Middlesex County.
Police in Delaware charged Jackson with a count of first degree reckless endangering for leaving the child in a bathroom at the gas station last Sunday.
Jackson was held at the Middlesex County Adult Correction Center in North Brunswick, N.J. in lieu of $750,000 bail, which was set by Superior Court Judge Dennis Nieves in New Brunswick, N.J.
Richard Sedlak from western Pennsylvania is a power company lineman who was passing through on the way to a job in Maryland. He stopped, intending to use the bathroom at a Shell gas station at 804 South College Avenue, near the University of Delaware. He got a key from the attendant and headed to the door, but heard crying from inside.
"He waited a few minutes, thinking there was a parent and child inside," said Lt. Brian Henry of the Newark Police. "But when the crying continued and nothing else happened he opened the door and found the child inside, alone."
After the child's picture was aired on television, including Eyewitness News, police received tips and were able to identify the girl.
The gas station where she was abandoned has an electronic surveillance system, but it wasn't working, investigators said.
The girl, who was living with her mother in North Brunswick, N.J., currently is in good health. She is in the custody of the Division of Family Services in Delaware.
The identity of the child's mother is being withheld at this time due to the on-going nature of the investigation. Police in Monsey, N.Y., have said a woman whose burned body was found in a park is connected to the case. They did not say if she was the baby's mother.
Anyone with information on the case is asked to call Detective Michael McGinn of the North Brunswick Police Department at (732) 545-3200, or Investigator Paul Miller of the Middlesex County Prosecutor's Office at (732) 745-4466.
