Mekhissi-Benabbad made his first appearances as a junior athlete in 2004, running at the 2004 IAAF World Cross Country Championships, where he was 61st in the junior race, and at the 2004 World Junior Championships where he was eliminated in the heats of the 3000 m steeplechase. He ran in the 1500 metres event at the 2006 European Cup, where he finished eighth. Mekhissi-Benabbad represented France at the 2006 IAAF World Cup, but only managed to finish eighth in the 1500 m event.