A 3-year-old girl was discovered in a Bronx apartment — along with the body of her mom, police said yesterday.

The tot was found in good condition in her crib at the home on Allerton Avenue near White Plains Road in Bronxwood at 7:30 p.m. Sunday by cops investigating a report of a gun shot.

It was not clear how long the 22-year-old mom had been dead, said cops who were not releasing her name pending family notification.

Investigators were questioning the victim’s boyfriend in connection with the slaying yesterday, but he has not been arrested.