A Brooklyn bus driver and a matron have been arrested for forgetting a sleeping 4-year-old girl in the back of the bus, leaving her to wander off alone Monday until she was reunited with her mother.

Antoliy Elkin, 76, and Galina Zabarnaya, 63, were charged late Monday with failure to exercise control of a minor for the blunder that left young Nicole Mendez to fend for herself, police sources said.

Elkin drove a bus full of youngsters to the Bam Bam’s Playhouse daycare center in Brighton Beach on Monday, ushered them off and parked the bus, sources said.

But neither he nor Zabarnaya, the matron, checked to make sure the bus was empty before leaving it, according to sources.

“Apparently the child was sleeping in the back of the bus,” said William Aubry, the NYPD’s commanding officer of citywide investigations.

Mendez scampered off the bus, and was found in Gravesend’s Calvert Vaux Park around 9:30 a.m. by a Department of Environmental Protection worker who turned her over to the police.

The cops, in turn, pored over surveillance footage to retrace her steps.

They also blasted out images of the wayward tot to the media, alerting Mendez’s mom, said Aubry.

Mother and child were reunited at the 60th Precinct stationhouse in Coney Island.

An owner of the daycare center stood by the privately employed workers Tuesday.

“They’re fully responsible for it. It’s a human mistake,” said the man, who gave his name as Gene. “They’re very responsible people.”

Elkin and Zabarnaya were awaiting arraignment Tuesday.