The trio, whom cops said were friends, had been playing in the Patterson Playground near East 145th St. and Morris Avenue when they all left the area about 6:30 p.m., according to the NYPD.
A police spokesman said they did not suspect criminality in the disappearance.
Alberto Correa, 20, who lives a block away from the playground, is 5-feet-3-inches tall, 109 pounds, was last seen riding an orange bicycle and wearing a white T-shirt, police said.
Chandler Roland, 10, who also lives near the playground, is 4-feet-11-inches tall, 70 pounds, and was last seen wearing a white T-shirt with pink sweat pants, cops said.
Amin Dawkins, 15, who lives on the same apartment building floor as Chandler, is 5-feet-5-inches tall, 110 pounds, and had been wearing a red T-shirt, blue jeans, and black sneakers, cops said.
Anyone with information is asked to call Crime Stoppers at (800) 577-TIPS (8477).