Hundreds of protesters took to the streets on Sunday on the first day of the conference.
The giant blimp of the UK prime minister was inflated at Castlefield Bowl ahead of a Reject Brexit – Defend Our Democracy event on Sunday afternoon, Yahoo News reported.
The 6m tall inflatable depicted Johnson dressed in blue shorts with red hearts and the word “Nigel” on, and a T-shirt showing a £350 million bus.
The Conservative Party conference is underway in Manchester as Johnson faces scrutiny over claims he touched a female journalist’s thigh.
It comes as the police watchdog decides whether or not to investigate the prime minister over his links to American businesswoman Jennifer Arcuri.
Demonstrators gathered on Oxford Road at about midday for a Shut Down the Tories event before marching through heavy downpours to Deansgate, where a rally was due to be held.
Shadow education secretary Angela Rayner was among those heading the march, holding a banner saying “No More Austerity”.
Others held placards saying “Tories Out” and “Defy Tory Rule”.