Iwelumo's father is Nigerian and his mother is Scottish. He won his first cap as a full Scottish international coming on as a substitute against Norway in a 2010 FIFA World Cupqualifier in 2008, notable for his missing an open goal from only yards out as the match finished 0–0 an event which Iwelumo has said "tortured" him. He had his first international start in a friendly against Argentina in November the same year.