In the 2004 indoor season, O'Dwyer recorded a new career best and a national record of 2.27 m to finish eighth in the final at the World Championships in Budapest, making him the first Irish athlete to reach the top of the world indoor rankings in any field event. Shortly after the Worlds, O'Dwyer broke the Irish under-23 record with a leap of 2.26 m at the high jump meet in Eppingen, Germany, edging closer to the 2.30-metre mark.