During the 2010–11 season, O'Brien picked up a hamstring injury for Bolton in the Premier League game against Aston Villa. O'Brien joined Leeds United on an initial one month's loan on 29 October 2010. Manager Simon Grayson said of the move "Andy has had a fantastic career, and has great experience. He's a leader and will be a valuable member of the squad for the next ." The move saw O'Brien re-join the club he started his career at, he was released by Leeds 17 years earlier as a 14-year-old. O'Brien was given squad number 40 and made his debut for against Scunthorpe United. In November 2010, O'Brien revealed that he would be interested in possibly making his loan move to Leeds permanent. O'Brien scored his first goal for Leeds with a header against Hull City. On 24 November, the loan was extended until 4 January 2011.