The individual – who has not been named – received medical attention during the race on Sunday, October 4 and later died..
Run 4 Wales, the event organisers, said: “We can confirm that a participant in this year’s event has sadly passed away.
“We’d like to acknowledge the event and hospital medical teams who reacted with great speed and professionalism.
“Our deepest sympathies go out to the runner’s family and friends.
“In respect of the family’s wishes, no further details will be released.”
In 2024, 37-year-old Stephen Jenkins died after collapsing at the finish line of the half marathon, while Nicholas Beckley, 35, died in 2019.
In 2018, Ben McDonald, 25, and Dean Fletcher, 32, also died after taking part in the race.
Details of the latest incident will be passed onto the coroner for potential investigation.
Cardiff Half Marathon is one of the largest events of its kind in the UK.
It attracts up to 30,000 runners and forms part of the SuperHalfs series, which includes races in Berlin, Valencia, Prague, Lisbon, and Copenhagen.
The course takes runners past many of Cardiff’s most famous landmarks, including Cardiff Castle, the Principality Stadium, the barrage, the Norwegian Church, and the Wales Millennium Centre.
This year’s event saw Kenyan runner Joyciline Jepkosgei set a new women’s course record, finishing in 1:05:40 and shaving 12 seconds off the previous record set by Edith Chelimo in 2017.
Gideon Kiprotich won the men’s race with a time of 59:34.
