The incident happened at around 1pm at the traffic lights by the Garda Station.
The pensioner in her early 70s was struck by a lorry while crossing the road.
She was pronounced dead at the scene – the N24 is currently closed to facilitate a forensic collision examination.
Diversions are in place via Ard Mhuire and Ash Park which is likely to lead to delays.
It is expected that the road will remain closed for a number of hours.
Gardaí in Clonmel are appealing for witnesses to the collision to contact them on 052 6177640, the Garda Confidential Line on 1800 666 111.
