Miller made his first-class debut in the Dolphins' final game of the 2007–08 domestic SuperSport Series, scoring a half-century in the first innings in which he batted.
Miller made eight appearances in the one-day MTN Domestic Championship competition of the same season, though his final match was abandoned after just three overs. Miller scored an average of 13 runs throughout the competition, which saw the Dolphins finish in fifth place in the league.
Miller earned his national call-up in May 2010 after a series for South Africa A against Bangladesh A, where he ended as the second-highest run-scorer.Miller made his Twenty20 International debut for South Africa on 20 May 2010 against the West Indies in Antigua. Miller, called up to replace the injured Jacques Kallis, dispatched the sixth ball of his innings for six and went on to top score as South Africa won by just 1 run. Two days later Miller made his ODI debut, also against the West Indies. He put in another good performance, scoring 23 not out and helping South Africa to victory. Miller was selected to play in Zimbabwe's tour of South Africa, during which he contributed in both ODI and T20 formats towards a resounding victory by the South Africans. He was then selected for the squad to play Pakistan in the U.A.E. during October and November 2010. He played in two ODI series, against West Indies and Pakistan, before being named in South Africa preliminary 2011 World Cup squad.