The 23-year-old victim was walking in Milton Street in Hamilton, South Lanarkshire, around 10.20am on Sunday when he was attacked.
Police said he had left his home and was heading towards Hamilton West train station when another man, who was walking in the opposite direction at Milton Street, stabbed the 23-year-old in the back of the neck as he passed by.
The attacker walked off and the victim was taken by ambulance to Hairmyres Hospital where staff describe his condition as stable.
The suspect is described as white, between 21 and 40-years-old, around 5ft 8in with a slim build and shaved hair. He was also wearing a navy tracksuit.
Detective Constable Stephen Divers said: “This was a random and totally unprovoked attack and it is vital that we trace the despicable individual responsible.
“I would appeal to anyone who was in the area of Milton Street yesterday morning who noticed a man matching the above description, or anything at all suspicious, to please get in touch.
“Anyone with information can contact Cambuslang CID via 101, quoting incident number 1332 of Sunday 25 March 2018. Alternatively you can call Crimestoppers on 0800 555 111 where details can be given in confidence.”