Ashley Agerenza, 19, has been charged with child abuse, resisting arrest and battery of a police officer after an incident outside Extreme Tan and Smoothies in St Petersburg, Florida.
Police said she first took the child inside the salon, but was told she could not leave the baby while she had a tanning session.
She then took the child back out to her car, strapped her into the car seat and turned on the engine, before returning to the salon.
A post on Agerenza's Facebook page read: 'Wit my lil mama then i might go out for the first time yay! dk if I can leave her tho...
'So maybe just a drink wen she asleep. love my baby!'