The lookalike sang versions of Wrecking Ball by Miley Cyrus and Uptown Funk by Mark Ronson and Bruno Mars, at one stage bringing out a puppet of the Prime Minister to use in the act.
The changed lyrics to the songs included “all I wanted to do was wreck the country”, as well as poking fun at the “strong and stable” phrase Mrs May used during the election campaign.
Dozens of pro-EU activists cheered along, many of who were wielding Liberal Democrat banners from the party’s conference.
Drew Galdron, who has been impersonating Mr Johnson for six years, said: “I don’t want there to be any monkey business in the Brexit talks - just piff-paddling fluff-diddling”.
Tom Brake, the Lib Dem Brexit spokesman, addressed the crowds after the performances ended.
He said: “Keep on campaigning. We are very much fighting for an exit from Brexit.”
Mr Galdron plans on attending the Labour Party conference in Brighton and the Conservative Party event in Manchester.