From
Melbourne, he had a background in
Australian Rules Football and came to athletics relatively late. He was
Victoria state champion in the under-20
5000 metres in March 2020, one of his first races. O’Donnell won his second national cross country title in wet conditions in Launceston, Tasmania, in 2024. O'Donnell had a successful 2025, despite suffering from stress fractures throughout the year. in August, he ran a personal best 7:34.43 for the 3000 metres in Sweden, finishing runner-up to
Andreas Almgren in Sollentuna. In September 2025, he competed over 5000 metres at the
2025 World Championships in
Tokyo, Japan, without advancing to the final. On 13 November, O'Donnell broke the Victorian Milers Club record for 3000 metres. In December 2025, O'Donnell won the Australian 10,000 metres title in Melbourne in a time of 27:59.65. That month, he was runner-up to Myers at the Australian World Championships Cross Country trials at Stromlo Forest Park, and was subsequently selected for the Australia team for the
2026 World Athletics Cross Country Championships in
Tallahassee, placing 45th overall.{{Cite web |title= 46th World Athletics Cross Country Championships ==Personal life==