A 5-year-old boy fell to his death Wednesday night from a balcony of his Williamsburg apartment, police said.

The little boy, Meisels Shimon, plunged from the fifth-floor balcony of the Wallabout Street building, near Middleton Street, just before 9 p.m.

His mother was home at the time, police said, but didn’t realize what had happened until she heard commotion from outside.

The boy was taken to Brooklyn Hospital Center by a private ambulance, police said, but he was pronounced dead there.

Police were investigating the circumstances surrounding the fall.