They, of course, beat Chesterfield 3-1 at Wembley in front of 35,663 fans thanks to goals from Josh McQuoid, Shaun Brisley and Britt Assombalonga.
Posh will be hoping history repeats itself on Sunday with Wycombe Wanderers standing between Posh and another trophy.
Many of those 2014 stars will no doubt be watching the latest crop in action. But whatever happened to those players once the dust had settled? Here we have all the answers.
You can get plenty more Wembley build-up here.
1. Bobby Olejnik
At the end of the 2013/14 campaign Olejnik was told he wouldn't be getting a new contract. Spells with Exeter City and Mansfield Town followed. In July 2020 Olejnik announced his retirement from professional football, aiming to fous on a career in the technology sector. Photo: Ben Hoskins
2. Shaun Brisley
Shaun Brisley is still playing, plying his trade at National League North side Alfreton Town. He left Posh to join League One rivals Scunthorpe United on 25 September 2014. Brisley turned vegan in 2017 after being introduced to the diet by his partner. Photo: Ben Hoskins
3. Mark Little
Mark Little left Peterborough after turning down a new contract offer on 5 June 2014. Spells at Bristol City, Bolton and Bristol Rovers. He is still enjoying a playing career, currently with Cymru Premier club Penybont. Photo: Pete Norton
4. Michael Bostwick
Michael Bostwick was voted as Peterborough's Player of the Year for the 2016/17 season. After five years at the club he signed for newly promoted League Two club Lincoln City on a two-year contract on 20 July 2017. He is currently at Boston United. Photo: Richard Heathcote