Paramedics were sent to the scene at Pinson Road, near Willenhall Memorial Park, on Tuesday evening.
The 19-year-old was approached by two men before being stabbed, a spokesman for West Midlands Police said.
Crews arrived just after 6.42pm and treated the victim for his injuries before he was taken to hospital, where he remains in a "serious" but stable condition.
A spokeswoman for West Midlands Ambulance Service said: "We were called to a patient in Pinson Road who’d reportedly been stabbed.
"We sent an ambulance, a paramedic officer and the MERIT car with a doctor and critical care paramedic on board.
"Crews treated one patient, a man, for potentially serious injuries and he was conveyed to hospital for further treatment."
CCTV is being reviewed as investigations continue – with police urging anyone with information to contact them via live chat or 101.
Crimestoppers can be called anonymously on 0800 555 111. Quote crime reference number 20WS/229561C/20.