Asim Khan, from Grangetown in south Cardiff, was fatally stabbed near a McDonald’s in the city in the early hours of this morning.
Emergency services were scrambled to the scene at 4.50am and paramedics performed CPR as they desperately tried to save Asim.
The young man was then rushed to hospital where he tragically died.
Police launched a murder investigation and a manhunt before later arresting a 27-year-old local man in connection with the incident.
The arrested man is currently in custody at Cardiff Bay Police Station.
Detective Superintendent Richard Jones, from South Wales Police Major Crime Investigation Team, said: “A young man has tragically lost his life early this morning and we are doing all we can to bring those responsible for the murder of Asim Khan to justice.
“CCTV shows a disturbance which starts in the street near McDonalds and moves towards the Oxfam store where Mr Khan sadly collapsed having sustained a wound as a result of being stabbed.
“Significant police enquiries are continuing in the area and we thank the local community, including businesses and visitors, for its understanding while a number of cordons remain in place.”
The dawn attack happened on the capital city’s main nightlife street, St Mary’s Street, part of which remains cordoned off to the public.
A large number of officers were still in the area this afternoon as well as a police helicopter with “significant” enquiries continuing, South Wales Police said earlier.
Witnesses described the suspect making-off initially towards Cardiff Central Railway station following the fatal attack.
Anyone with information relating to the attack is asked to call 101, citing the reference number 1900265784.