O'Donnell made his senior debut during the pre-season Waterford Crystal Cup in 2013. It was a successful campaign for Clare, as a 1-21 to 1-13 defeat of Tipperary gave O'Donnell a winners' medal in that competition. Later that year he made his championship debut at left corner-forward in a Munster quarter-final defeat of Waterford. The rest of the championship campaign saw O'Donnell dropped from the starting fifteen for several games, however, he was a late addition at full-forward for Clare's All-Ireland final replay against Cork. His selection seemed surprising but was justified, as O'Donnell scored a hat-trick of goals in the first nineteen minutes of the game. Further goals from Conor McGrath and Darach Honan secured a 5-16 to 3-16 victory following a classic championship decider. The win gave O'Donnell an All-Ireland medal, while he was also named man of the match. In October 2013, O'Donnell won the Opel Player of the Month Award for September. In June 2021, he received a heavy blow when training with the Clare team that left him with a serious concussion. It ruled him out of the 2021 Championship. He returned to the Clare panel in March 2022. On 21 July 2024, he started in the full-forward line as Clare won the All-Ireland for the first time in 11 years after an extra-time win against Cork by 3-29 to 1-34, claiming their fifth All-Ireland title. O'Donnell won his third All Star and was selected as GAA/GPA Hurler of the Year at the end of the 2024 season.