Police have launched an investigation after the child was cut on the arm in broad daylight.
The 16-year-old was attacked in West Bromwich Ringway on Monday afternoon.
Police have arrested a 17-year-old boy in connection with the stabbing which happened at around 3.35pm.
The teenager was arrested at Smethwick Galton Bridge Railway Station a short time later.
A West Midlands Police spokesman said: "The 16-year-old is believed to have suffered a cut to his arm, but the injuries are not life-threatening or life-changing.
The victim is believed to have presented himself to an ambulance that was already on Spon Lane, which was treating another patient in an unrelated incident.
A West Midlands Ambulance Service spokesman said: "The ambulance crew treated the patient on the scene before he was taken to hospital for further checks."
Anyone with information is asked to contact police, quoting log number 1477 of October 7.