They have followed the side through good and bad days up and down the line to play their part.
Here we pay tribute to that fantastic support in this picture gallery over the last four seasons.
We have pics from a pre-season friendly at Bedford Town on 10th July 2021 and fans ahead of the EFL Cup game with Plymouth on 10th August 2021.
There’s plenty of pics from league games, including Bolton, Fleetwood, Northampton, Derby and Birmingham.
No galllery would be complete without a mention of two Wembley wins – and how could we forget victory over Cambridge?
Take a look and see how many of your friends and family feature.
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49. Posh 1 Wigan 0
Mahamadou Susoho's first goal for Peterborough United gave Posh a much-needed win over Wigan. Photo: David Lowndes
50. Birmingham City 0 Posh 2
Peterborough United delivered a brilliant performance to stun Birmingham City and lift the EFL Trophy for the second season in succession. Photo: David Lowndes
51. Birmingham City 0 Posh 2
Peterborough United delivered a brilliant performance to stun Birmingham City and lift the EFL Trophy for the second season in succession. Photo: David Lowndes
52. Birmingham City 0 Posh 2
Peterborough United delivered a brilliant performance to stun Birmingham City and lift the EFL Trophy for the second season in succession. Photo: David Lowndes