Before playing in the NHL, Halák played 9 games with Bratislava in the Slovak Junior league, 12 games with HC Slovan Bratislava of the Slovak Extraliga and 47 games with the Lewiston Maineiacs of the Quebec Major Junior Hockey League (QMJHL). He was drafted with the 271st overall pick by the Montreal Canadiens in the 2003 NHL Entry Draft. Before he played with the Canadiens, he would play for their AHL-affiliate Hamilton Bulldogs.