But despite Paddy Wallace's try early in the second-half to give the visitors the lead for the first time, the New Zealand Maori recovered to claim the win - adding the Irish scalp to a collection that already included Australia, France and the British and Irish Lions.
The Maori made a fantastic start to the game and touched down through Hosea Gear and Dwayne Sweeney after 14 minutes.
But Sexton converted six penalties and the Irish were level at the interval.
And things got better for Ireland immediately after the break as Wallace scored their only try of the game.
Good work saw the tourists steal the kick-off and after a couple of drives, captain for the day Geordan Murphy cut through a gap and found Wallace in support on his shoulder to score.
After Sexton and Luke McAllister traded penalties, Karl Lowe scored on his Maori debut following a superb run from Sean Maitland with Willie Ripia converting to regain the lead.
Ireland's response was immediately and Sexton slotted over a penalty but the Maori took the lead again when Munster flanker Niall Ronan was penalised for handling in the ruck.
Sexton had the chance to level late on, but the Leinster man missed his first kick of the night and couldn't add to his points tally of 23 - allowing the Maori to hold on for the dramatic win.