The incident took place at a premises on the High Street in Newport at around 2.40am on Saturday.
Police have said that the victim is currently in hospital in a "serious but stable condition".
Officers said that two arrests have been made in relation to the incident.
A 22-year-old man was arrested on suspicion of assault and a second man, 19, was arrested on suspicion of assisting an offender.
Both have been released on bail while the investigation continues.
Police are also seeking a third man in relation to the incident.
Detective Inspector Jo Whitehead, said: “This is a really sad incident where an innocent young man enjoying a night out with friends was assaulted and sustained very serious injuries.
"Thankfully, he is now in a stable condition but the outcome was almost very different.
“We are actively searching for a third man in relation to the assault and I would urge anyone who witnessed the incident to please get in touch with us as soon as possible.
“I’d like to thank everyone who has helped us so far, and to offer reassurance that this was an isolated incident.”
West Midlands Ambulance Service said they had provided trauma care at the scene before taking the man to hospital.
A spokesman said: “We were called to reports of an assault on High Street, Newport at 2.47am on Saturday. Two ambulances, a paramedic officer and a MERIT trauma doctor and critical care paramedic attended the scene.
"Upon arrival we found a man with serious injuries. He received advanced trauma care from ambulance staff at the scene and was conveyed to hospital for further assessment."
Anyone with information is asked to get in touch with the reactive CID team on DL-GCID@westmercia.pnn.police.uk quoting incident number 78i of November 19.
Alternatively people can contact Crimestoppers anonymously on 0800 555 111.