Millwall players Jake Cooper and Byron Webster were pictured riding Boris Bikes through London after their League One Play-Off Final win over Braford on Saturday.
The pair - still dressed in club tracksuits - were snapped after the game with winner's medals hanging proudly from their necks.
Webster played every minute of the club's 1-0 victory over Bradford, while Cooper was an unused substitute as he marked the end of a loan spell from Reading with promotion to the Championship.
Twitter user @wrightsnake posted the image, adding: "There's a couple of Millwall players, wearing their medals, getting on Boris Bikes outside Warren Street tube."
It was later shared by the club's official twitter feed with accompanying caption: "The night is young for Byron Webster and Jake Cooper."
Steve Morison's late volley sealed Millwall's promotion to the second tier at the national stadium on Saturday.
Millwall goalkeeper Jordan Archer made a fine save to deny Bradford's Billy Clark in the first Period before Morison's strike sent Millwall back to the Championship for the first time since they were relegated in 2015.
"Steve [Morison] is our talisman," said Millwall boss Neil Harris.
"He's an integral part of how we play and when you need that moment of magic he's the man."
The Lions, who lost last year's League One Play-Off Final, have now won promotion to the second tier a record six times.
