In his homeland, Martinović played for Rad, BSK Borča, OFK Beograd, and Smederevo, before moving abroad to Romania in early 2009. He is arguably best remembered for kicking a Petrolul Ploiești fan who ran onto the field and punched his Steaua București teammate George Galamaz in the head during a Liga I game in October 2011. Despite receiving a red card by the referee, Martinović was later praised for his reaction by the media and the fans.
In early 2013, Martinović was transferred to Chinese club Wuhan Zall. He left Asia after just six months and returned to Serbia to join Red Star Belgrade.