Chris O'Donnell ran the anchor leg for the Irish mixed 4x400 metres relay team that reached the final at the Tokyo 2020 Olympic Games, finishing eighth in 3:15.04 - the first Irish team to compete in an Olympic relay final. The event was making its Olympic debut at those Games.
He returned in the mixed 4x400 metres relay at Paris 2024.
O'Donnell grew up in Sligo playing football with Benbulben FC, and took up sprint training as a teenager to improve his speed on the pitch. He is from Grange, County Sligo.