The teen who allegedly fatally stabbed a rival to death with a box cutter during an after-school brawl on Wednesday turned himself in to cops late on Friday, police said.

Jovani Cubias, 17, was stabbed once in the chest outside Lindsay Park at the corner of Lorimer Street and Montrose Avenue in Williamsburg at 4:30 p.m. He was rushed to Bellevue Hospital, where he was pronounced dead an hour later.

Dante Malay, 19, was charged with manslaughter, assault and criminal possession of a weapon, cops said.