South Wales Police officers are releasing CCTV images of a suspect involved in the stabbing that happened in Callaghan Square at 9.13am on Friday 20 March 2020 near the British Gas building.
Following the incident, one man was arrested, charged and remanded and was sentenced to 18 weeks imprisonment for public order.
Officers now have CCTV images and are appealing to the public to help trace the second man involved in the incident.
If anyone has any information in relation to this man or recognise this man, they are asked to contact police on 101 quoting ref: 2000097993 or contact Crimestoppers free and anonymously on 0800 555 111.
At the time of the stabbing, a 31-year-old man was taken to the University Hospital of Wales, Cardiff, with leg wounds.
It is believed those involved are known to each other.