Having first turned professional in 1991, Dunn has been ranked within the top 64 players in the world since 2002, reaching his highest ranking, at 32nd, in October 2010. He has enjoyed the best form of his career since 2013, reaching the last 16 stage of three tournaments, and the semi-finals of the 2014 China Open and the 2015 Ruhr Open. He announced his retirement from the game after losing in the third qualifying round of the 2020 World Championship.