The world number one was dominate throughout against the Irishman who rarely troubled last year’s World Championship winner.
Playing his first match since winning the China Open, Selby was in complete control cruising to an 8-0 lead before O’Brien ended the first session by getting his first frame on the board.
But the Jester from Leicester needed just an hour of the final session to secure a place in the second round, winning 10-2.
He will next play the winner of the first round tie between Ryan Day and Xiao Guodong.
The opening day also proved to be an impressive one for qualifier Stephen Maguire after he thrashed one of the top seeds Anthony McGill 10-2.
Maguire, a former two-times World Championship semi-finalist, appears to have found his top form again after comfortably winning all his qualifying matches and then knocking out fellow Scottish star McGill in dominating style.
Leading 7-2 after the opening session, Maguire won all three of the evening session frames to book his place in the next round. It was Maguire’s first win at the Crucible since reaching the semi-finals in 2012.
Next up for the Glaswegian will be either joint favourite for the title Judd Trump or Rory McLeod.
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