Adrian Gomez was arrested at about 12:15 p.m. The attack occurred at the suspect's apartment on the 10000 block of Imperial Avenue around 3:05 p.m on Tuesday.
Gomez was preparing to cut Jeff Valenz's hair when he suddenly stabbed Valenz three times for no apparent reason, police said.
Valenz, 23, of Stanton, suffered stab wounds to his neck, left elbow and left shoulder. With a smock still on, he escaped, driving to a school parking lot where police found him.
"He backed up away from the scene, just trying to get out of there as soon as possible," Lt. Benjamin Stauffer said.
Valenz was treated at UC Irvine Medical Center in Orange and is expected to recover.
Gomez has previously worked at a number of places as a barber, including another location in Garden Grove. The manager said he left because he wasn't making enough.
CNS contributed to this report.