A violent creep sucker-punched a 71-year-old woman, breaking her jaw, while she was walking on a Brooklyn sidewalk, police said.

The suspect walked up to the victim on New York Avenue near Lefferts Avenue at about 5:30 p.m. Sept. 19 and cold-cocked her, according to video released by authorities.

The woman was knocked unconscious and collapsed to the ground, cops said.

She was rushed to the hospital, where it was discovered that she suffered a broken jaw and needed stitches to close a wound on her mouth.

The suspect is still at large, police said.