A violent Bronx mugger cold-cocked a man with a knee-buckling punch before stealing his headphones, video of the brutal attack shows.

The suspect went up to the 38-year-old man early Sunday in front of a grocery store on West 183rd Street near Aqueduct Avenue in Fordham Heights, cops said.

The mugger, dressed in a red jacket, a gray Jordan sweatsuit and a gray hat, spoke to the man for a few seconds before launching his attack, video released by the NYPD shows.

He socked the man in the face with a right hook, sending him staggering back to lean on a parked car, the video shows.

The victim tried to stop the mugger by holding out his hands and shielding himself, but the suspect continued to land blows.

The thief then wound up and hit the man with a knockout blow that sent him to the pavement, the video shows.

He continued punching him as he grabbed his headphones and ran off.

The victim was taken to the hospital for head and neck injuries, police said.

The suspect was last seen running away on West 183rd Street.