The airline confirmed flight EZY1963 made an unscheduled landing in the city on Sunday (August 19) after the passenger became abusive towards flight crew.
Passengers told the Gibraltar Broadcasting Corporation the man escorted from the flight was “drunk” and “rowdy”.
Two other passengers also disembarked in Porto. The aircraft eventually arrived in Gibraltar around an hour late.
An easyJet spokesperson, The Sun reports, said: "easyJet can confirm flight EZY1963 from Manchester to Gibraltar diverted to Porto on August 19 due to a passenger onboard behaving disruptively.