The victim suffered knife wounds to his body, neck and shoulder during the attack in Johnstone, Renfrewshire.
Paramedics took the builder to Paisley’s Royal Alexandra Hospital where his condition has been described as stable.
Witnesses told the Paisley Daily Express that victim was doing cladding work in the area when he was targeted.
One passerby said: “The guy was involved with the building work in the street when the attack took place.
“Cops sealed the street off and there must have been around six or seven police cars here, along with the ambulance.
“It looked like the guy was being treated in the ambulance for a while before they headed to the hospital.
“It’s not the kind of thing you expect to see first thing in the morning, that’s for sure.”
A Police Scotland spokeswoman said: “At around 9.45am, police were called to a report of a 22-year-old man having been assaulted on the High Street, Johnstone.
“Police and emergency services attended and the man has been taken to hospital by ambulance for treatment to injuries to his shoulder and neck.
“Enquiries are continuing. Medical staff describe his condition as stable and the injuries are not believed to be life-threatening.”
The victim works with Paisley construction company CGC.
A spokesman for the firm told the Paisley Daily Express : “We are shocked and concerned to learn that a CGC employee suffered injuries as a result of an alleged incident in Johnstone this morning.
“We continue to monitor the situation closely.”