The grand jury indicted Anthony Jerome Towles, 55, on Oct. 2 for the mid-July incident; he was then arrested on Saturday and has since posted $25,000 bond, The Baltimore Sun reported.
Investigators said that on July 5, Towles was supposed to bring the girl to daycare, but instead drove to his home and went inside to sleep, leaving the girl in the car.
The girl was later found dead.
A medical examiner ruled at the time that the girl's death was accidental and was due to excessively high body temperatures.
Towles faces up to 10 years in prison if he is found guilty.