Sexton's Ireland fly-half rival Ronan O'Gara kicked four penalties of his own and Munster were awarded a penalty try in the closing stages as they had to settle for a losing bonus point.
Tony McGahan was also dealt a blow as Ireland winger Keith Earls was helped off inside the opening stages with a suspected knee injury.
Inevitably, given the underdogs tag by most bookmakers, reigning champions Munster came out firing and early pressure resulted in O'Gara opening the scoring with a penalty having seen his initial drop goal attempt charged down.
But Leinster responded strongly claiming the restart before Donnacha Ryan was pinged for an offence at the ruck allowing Sexton to slot an equalising penalty on nine minutes.
Ryan was again the offender at another ruck, as he came around the side, allowing Sexton to nudge the hosts into the lead shortly afterwards.
The battle of the breakdown was fast becoming a feature of the match as a Leinster offence for coming in at the side allowed O'Gara to level the scores on 19 minutes.
But straight from the restart Sexton was able to restore Leinster's advantage with Niall Ronan this time the guilty party before the fly-half made it 12-6 on 28 minutes although the home team will have felt they could have had much more.
Jamie Heaslip and Cian Healey drove deep into Munster territory before Mike Ross saw space open up in front of him only for Lifeimi Mafi to pull off a try-saving tackle to stop the Ireland prop in his tracks.
Leinster did have the consolation of a penalty but that deficit was reduced with another O'Gara three pointer after a maul was illegally pulled down.
Sexton though had the last word in the half after BJ Botha was penalised in the scrum to give Leinster a 15-9 halftime advantage.
Munster came flying out of the traps after the break with Mafi and Paul O'Connell carrying well before a Leinster offence at the ruck allowed O'Gara to once again reduce the deficit with his fourth penalty of the night.
Sexton responded in kind when Ryan gave away his third penalty and Leinster started to use their back division to better effect as they made some hard yards inside the Munster half.
And it was one of those backs, full-back Kearney, who extended the advantage with an opportunistic drop goal just before Denis Leamy was yellow carded for persistent infringement.
From the resulting penalty, Sexton nudged Leinster out to 24-12 ahead to put the home team in a seemingly unassailable position.
But Munster showed their depths of character by refusing to bow down without a fight and Heaslip was sinbinned just as Leamy emerged from his ten minutes off.
And referee Pascal Gauzere made himself an even more unpopular figure amongst the majority inside the Aviva Stadium when he awarded a penalty as a rampaging Munster scrum was illegally halted in its tracks.
O'Gara added the conversion point but despite a frantic finish Munster only had a losing bonus point to show for their efforts after a titanic armwrestle against their great rivals.
|Leinster Rugby Score Card|
|Munster Rugby Score Card|