In his debut for the Australia national baseball team, he hit .333 in the 2005 Baseball World Cup, playing error-free ball in six games at shortstop; he split time at short with Rodney van Buizen in his debut tournament with the senior team.

Harman scored the 7th-inning go-ahead run against the Cuban national team in a game Australia lost, 3–2, in 10 innings.

Harman sparked the winning rally in the bottom of the ninth inning against the Dutch national team closer Michiel van Kampen.

[2] On 20 May 2010, Herald Sun reported that Harman had been suspended for 14 months by the Australian Sports Anti-Doping Authority for failing to declare his whereabouts.

Harman played his last professional baseball game 11 February 2017 with the Aces in the 2016-17 ABL Championship Series against the eventual champion Brisbane Bandits.