On 16 August 2010, Majstorović signed a two-year deal with Scottish Premier League club Celtic on a free transfer. Majstorović made his Celtic debut in the Europa League match against Dutch side FC Utrecht on 19 August 2010 in a 2–0 victory and his SPL debut three days later in a 4–0 win at home against St Mirren. Majstorović captained the side to a 2–1 victory over Kilmarnock when captain Scott Brown went off injured, captained the side again three days later against Inverness Caledonian Thistle in a League Cup tie which ended in a 6–0 win for Celtic. Majstorović scored his first goal for Celtic on 9 January 2011 in a 2–0 Scottish Cup win against Third Division side Berwick Rangers. He scored his first league goal for Celtic in a 3–1 win over Dundee United on 13 February 2011 at Tannadice. Majstorović played the full 90 minutes, picking up a yellow card, as Celtic won 3–0 against Motherwell in the 2011 Scottish Cup Final.