Clifford was placed 25th in the list, rising ten places and moving above Freud Communications founder Matthew Freud.
The MediaGuardian said of Clifford: 'He remains synonymous with tabloid scoops and for being the person the man or woman in the street would go to if they have a story or a crisis, from honeymoon murder suspect Shrien Dewani to former Big Brother contestant Imogen Thomas.'
The paper added: 'Clifford also played a role in one of the biggest media stories of the past year, having been one of the first to accept a payout from the News of the World over alleged phone hacking.'
Freud, said to be 'close to the heart of David Cameron's government' was placed 31st, behind his wife Elisebeth Murdoch who was at 23.
Other PR professionals to make the list were Brunswick founder Alan Parker, who rose a single place to 65th, remaining ahead of City rival Finsbury founder Roland Rudd at 75th.
Chime Communications founder Lord Bell was in 79th position, having not been on the list last year.
Overall, Facebook founder Mark Zuckerberg topped the list, ahead of Twitter executive chairman Jack Dorsey and Google chief executive Larry Page.
Sir Martin Sorrell, group chief executive of WPP, owner of Hill & Knowlton, Ogilvy and Finsbury, rose three places to 8th position.
News Corporation chairman Rupert Murdoch slipped two places to sixth, while his son James Murdoch, NewsCorp's deputy chief operating officer, dropped three places to 11th.