The stabbing was reported at about 11 a.m. near the intersection of South Fair Oaks and Iris avenues, Capt. Dave Verbrugge said.
The victim was taken to a hospital with moderate stab wounds to his arm and upper body, Verbrugge said.
The suspect, whose name has not been released, was arrested on suspicion of assault with a deadly weapon, he said.
South Fair Oaks Avenue remained closed between Iris Avenue and El Camino Real as of 12:15 p.m. while investigators searched for evidence related to the stabbing, Verbrugge said.
He did not know when the road would reopen.