On what will go down as one of the greatest days in the nation's rugby history, Ireland secured the clean sweep on home turf for the first time since 1948, and the first time ever in Dublin.
It is only Ireland's fourth-ever Grand Slam - their first since 2018 - and they clinched it with a hard-fought triumph over rivals England on St Patrick's weekend.
Hearts were set on a rare Grand Slam, though, and many had tipped them to ease to a fifth win out of five against an England side that suffered the humiliation of a record home defeat at the hands of France last weekend.
However, England produced a much-improved performance from that Twickenham debacle and ran Ireland close for much of the game despite losing Freddie Steward to a controversial red card on the stroke of half time.
Steve Borthwick may rue what might have been had the game stayed 15 against 15, with the gap between the two sides standing at just one point until the final 20 minutes, when Ireland began to make their numerical advantage count with three late tries.
Sexton's big moment arrived after 18 minutes when he knocked over a penalty to move clear of Ronan O'Gara - his compatriot and predecessor in the Ireland 10 shirt - as the leading points-scorer in Six Nations history.
Dan Sheehan scored the only try of a fiercely-contested first half as Ireland went into the break with a 10-6 lead, although it was Steward's red card right at the end of the half that perhaps had the most telling impact in the end.
The England full-back appeared to be protecting himself and pulling out of a tackle after a knock-on when he collided with Hugo Keenan, and a TMO review ruled that it was a dangerous contact on the head with no mitigating factors, resulting in a contentious red.
Borthwick's side fought valiantly while a man down, and Owen Farrell - back in the starting XV against the team managed by his father - kicked his third penalty of the day to close the gap to one.
However, Ireland's 15 men began to surge clear in the final 20 minutes as Robbie Henshaw went over for a nerve-settling try before Sheehan touched down for his second of the night.
There was a brief England riposte as Jamie George scored to ensure there could be no accusations of them throwing in the towel, as was the case after the defeat to France, but a further sin bin left them with 13 on the pitch and Rob Herring put the gloss on the Irish party with a fourth try to clinch the bonus point late on.
While the final scoreline perhaps flatters the home side, their status as Grand Slam winners does not and the top-ranked team in world rugby will be among the front-runners to claim a first World Cup title later this year.
It would arguably take World Cup glory to surpass today as perhaps the greatest in their history, having achieved the dream combination of winning the Grand Slam in Dublin against England on St Patrick's weekend.
England, meanwhile, end the Six Nations with a losing record, sitting fourth behind Ireland, France and Scotland.No Data Analysis info