The Official Online RBS 6 Nations Store is open. The store has everything you need to get behind your team during the RBS 6 Nations, plus the store is now fully stocked with a much wider range of rugby merchandise.
Fionn Carr scored two tries inside the opening 22 minutes, with Miah Nikora converting both but Ireland full-back Rob Kearney responded with a score of his own as Leinster trailed 14-8 at the interval.
Sexton had kicked one penalty in the first half and was successful with two more attempts after the break to level the scores in the 69th minute.
And the 24-year-old knocked over the drop goal with a minute left to secure the win and send Leinster four points clear at the top, while Connacht remain rock bottom.
In the only other Magners League fixture of the day Newport-Gwent Dragons won the all-Welsh affair with Ospreys 28-20.