The 35-year-old Labour MP caused one of the biggest upsets on the night when he took the Hallam seat from the former deputy prime minister.
After delivering a quickly-written victory speech, O'Mara headed back to West Street Live which he runs with a group of friends.
Speaking to the Guardian, he revealed how he celebrated his election victory and his busy schedule in the days which followed.
He said: "There may have been some refreshments, and I may have gone home at 6am."
Despite his late-night antics, the first-time MP wasted no time in getting to work and headed for a press event at Forge Dam park and then a rally at city hall.
Rumours circulated on Twitter that, on the night of the election, O'Mara was so surprised by his impending victory that he was forced to rush and buy a suit from Tesco.
However, he told the Guardian that in fact he was wearing a blazer which he had borrowed from his father.
Earlier this month, West Street Live joked on Facebook that they had offered Nick Clegg a new job as a regular on the turntables.
The city-centre bar said that 'Cleggers Plays Pop' was waiting for the former Liberal Democrat leader and urged him to get in touch.