In August 2010, Hartø became just the fourth amateur to win on the European Challenge Tour when he captured the ECCO Tour Championship.
He turned professional shortly thereafter, and won the Roma Golf Open in late October. This feat marked him as the fastest player to achieve to two titles in Challenge Tour history. Hartø then continued his hot streak, finishing tied-for-sixth at the European Tour Q-School, thereby earning full playing privileges for 2011. His best finish of 2011 was 14th at the Austrian Golf Open.
2010: ECCO Tour Championship, Roma Golf Open