The appointment does not affect the position of Gawain Towler, UKIP’s chief spin doctor, who will be "taking a more active role in Brussels", according to a party source.
O’Flynn will leave his post at the newspaper next month to head the UKIP comms effort ahead of the 2014 and European and UK local elections.
He will also be standing for the party in the European elections as the lead MEP candidate in the East of England constituency.
He has 18 years of experience as a Fleet Street political journalist. He has spent the past eight years as the chief political commentator for the Express.
Nigel Farage, UKIP leader, said:" I have known Patrick for a long time and was delighted when he showed his support for the party by standing as one of the most high profile, high calibre MEP candidates for UKIP in May.
"I am thrilled that he has now agreed to steer the team through the elections this year in this new role and am excited about all the party will gain from his insight and experience."
Party chairman Steve Crowther said: "Patrick is already a deeply valued part of the UKIP team. We are extremely proud to announce that he has now been appointed as our new director of communications."