Moira will swap control of the creative department's 30 teams for a full-time "ambassador" role in which he will help the agency's new-business drive.
Studzinski joins as the executive creative director in a deal brokered by Dave Droga, the former Saatchis creative chief, who was appointed Publicis' worldwide creative director at the end of last year.
Studzinski's move out of Charlotte Street, where he produced a string of award-winning work for the Army (now a Publicis client), Toyota and Habitat, comes less than a month after a departmental restructure by the Saatchis executive creative director, Tony Granger, in which his head of art title was scrapped.
Studzinski's arrival at Publicis coincides with other senior management changes in which Grant Duncan and Derek Morris will no longer share the chief executive's job they took on when Richard Hytner stepped down as the chairman last year.
Hytner, soon to complete his sabbatical on the London Business School's Sloan Masters MSc programme, will not return to the London agency but is likely to take a more senior role within Publicis Groupe.
Duncan becomes the sole chief executive while Morris reverts to his original title of chief strategic officer. Duncan insisted the change was not because the splitting of the chief executive role hadn't worked, nor was it a demotion for Morris.
"We now have an expanded department, including planning, direct marketing, interactive and brand consultancy which will all be under Derek's control," he said. "It's a full-time job for him and we want complete clarity in our structure and to focus on what each of us does best."
The £278 million-billing agency will now be run by a management team of Duncan, Morris, Moira, Studzinski and the newly appointed chief finance officer, Michel Karan.
Studzinski, 33, joined Saatchis from college and remained there apart from an eight-month interlude at Bartle Bogle Hegarty. His awards include a D&AD Pencil and Campaign Press Award.
He said: "The opportunity to go to an agency like Publicis, with so many fantastic clients and iconic brands, is something anybody would jump at."
Moira said: "I knew when I became chairman as well as the executive creative director last year that this would be a transitional arrangement and I'm very cool about that because I believe the time is right for a new boss of the creative department."
One of Studzinski's key tasks will be to boost the quality of the agency's print output.
"While our TV reel is strong we could do with some improvement in our print work," Moira added. "Because Nik comes from an art direction rather than a copy background he's well qualified to do something about it."