A Brooklyn man was robbed after falling asleep on the stoop of his apartment building following a night on the town, police said Saturday.

The 19-year-old had walked home from a booze-drenched night out at The Legend KTV, a karaoke bar on 61st Street in Borough Park, but couldn’t make it up to his apartment following the nearly one-mile walk to his apartment on 56th Street near 5th Avenue — passing out on the front stoop, instead, his father told The Post.

“My son drink too much alcohol so maybe around 5 a.m. he was sleeping right here,” said his father, who identified himself as Li, as he stood next in front of his building.

Video provided by police early Saturday showed that as the man was snoozing on the stairs around 5 a.m., an opportunist walked up and pulled his Apple iPhone from a back pocket.

The thief is later seen in the footage reaching around to the teen’s front and pulling a wallet containing $400 cash.

The victim appeared to wake up during the brazen robbery, but not before it was too late.

Police provided additional photographs of the bearded crook, who was wearing a dark blue shirt and a turquoise backpack. He was described as being approximately 5-foot-8 and 180 pounds.

Additional reporting by Oumou Fofana