When he was a child, in 1991, his family moved to Szombathely, where he played his first matches for the local football team Haladás and made his debut in the NB2 league at age 15.

He then led Sampdoria to win the 2007–08 Campionato Nazionale Primavera title, and also took part at the 2008 UEFA European Under-19 Championship captaining the Hungary under-19 national team.

On 15 April, Koman was interviewed after the victory against Metz; he iterated he is expecting his first goal and enjoyed playing in Ligue 2.

[11] On 12 November 2014, Koman was named by American digital media company Bleacher Report as one of the most notable free agents available for the 2014–15 season, along with Víctor Valdés and Simão.

[12] Due to lack of playing time with Krasnodar, in the 2013 summer transfer window, Koman was loaned out to fellow Russian league club Ural Sverdlosk Oblast.

[13] On 15 May 2014, he scored his first goal in the 2013–14 Russian Premier League season on the 30th matchday against Volga Nizhny Novgorod, in the 45th minute.

[15][16] On 1 August 2015, he scored his first goal for Diósgyőr in the 2015–16 Nemzeti Bajnokság I match in a 2–1 defeat against title-holders Videoton at the DVTK Stadion, Miskolc.

Koman was named to the Hungary senior team by head coach Erwin Koeman for the friendlies against Germany and the Netherlands in late May and early June 2010 respectively.

Koman scored his first international goal against Moldova at the Szusza Ferenc Stadium in a UEFA Euro 2012 qualifying match,[23] where Hungary won 2–1.

[28][29] On 10 September 2013, Koman provided two assists – one for his former under-21 teammate Krisztián Németh and one for Tamás Hajnal – in a 5–1 victory over Estonia in a 2014 World Cup qualifier at the Ferenc Puskás Stadium.