It comes as the agency, which has just won a major account with eBay, prepares to move from Bayswater to parent company Omnicom’s London flagship office on Southwark Street, Bankside, in August.
In his new position, Zackheim will join the agency’s London’s creative, digital and strategy team led by Jo Patterson, head of strategic planning.
He will work with creative content director Ruby Quince and Simon Sanett, associate director for digital and content strategy, on developing Porter Novelli’s "visual and contextualised content offer for clients", the agency said.
Zackheim spent 12 months as ITV News' deputy editor before leaving last year, having previously worked for Channel 5 and BBC Radio 5 Live.
Porter Novelli London MD Fenella Grey said: "Richard operates at the pace of news, and in building around our core expertise of tech, creative, strategy and now news, we have a differentiated and integrated content offer for a visually reliant world."
Porter Novelli will become the latest Omnicom agency to move to the firm’s Bankside HQ.
Last summer Omnicom confirmed to PRWeek that it would move some of its UK PR agencies, including Ketchum and Porter Novelli, into the new premises, although the exact timings were not announced. FleishmanHillard, which later merged with stablemate Fishburn, had earlier moved to the location.