Shelbourne pipped holders Peamount United at the post to be crowned Women's National League champions.
A dramatic final-night turnaround saw leaders Peamount slip up at home to Galway.
Shels went into their home game against third-placed Wexford Youths two points adrift of the Newcastle club.
But a 3-2 victory for the northsiders coupled with Peamount turning a two-goal lead into a 5-2 defeat saw Shels leapfrog Peamount into top spot.
In doing so, Shelbourne won their first WNL title since 2016 having hit the post in each of the last three campaigns, finishing runner-up each time.
Jessica Stapleton opened the scoring for Noel King's side on 22 minutes against Wexford.
Noelle Murray doubled that lead just a minute later from the penalty spot.
Stapleton scored her second of the night shortly after half-time to leave Shels well in command.
Peamount were level at the break with Galway meaning the top two were level on points after 45 minutes.
𝐂𝐇𝐀𝐌𝐏𝐈𝐎𝐍𝐒 🏆 pic.twitter.com/xRZidGBYOO
— Women's National League (@LoiWomen) November 13, 2021
But Wexford hit back at the interval, with a brace from Kylie Murphy leaving things on a knife edge.
But Shelbourne held on to secure victory and the title, just one point clear of their rivals, to be crowned league champions.
Shels can complete the double when they face Wexford in the FAI Women's Cup final next on 21 November.
For Peamount, Áine O'Gorman's header wrapped up the Golden Boot award for Top Goalscorer.
An own-goal from Galway keeper Leah Hayes Cohen doubled the advantage and put the holders firmly in control.
🗣Manager Thoughts| James O’Callaghan reflects on tonight’s defeat and Peamounts season🟢⚫️ pic.twitter.com/eDQ2dOwtph
— Peamount Utd FC (@peamountutd) November 13, 2021
However, goals from Emma Starr and Lynsey McKey had the teams all square at half-time.
After the break, Galway went ahead when a Shauna Brennan cross made its way into the back of the net.
Sooner after, ex-Peamount winger Julie-Ann Russell and sub Abbie Callanan completed the scoring.
Elsewhere, Athlone Town and Bohemians drew 1-1, while DLR Waves had a 3-1 win away to Treaty United.