The 15-year-old suspect was charged early Sunday with murder and criminal possession with a weapon, in connection with the killing of Ethan Reyes of Yonkers.
Authorities say that at around 3 p.m. police responded to reports of a crime in progress inside the 137th Street/City College subway station in Hamilton Heights.
When officers arrived on the scene, they discovered Reyes on the northbound 1 train platform with a stab wound to the abdomen.
Reyes was rushed to Mount Sinai St. Luke's, where he was pronounced dead.
The suspect's name has not been released.
The motive behind the attack remains under investigation, but officers say it was not a random attack.