PR industry veteran Seltzer said he is resigning 'to pursue other opportunities', and is set to leave at the end of this month.
Twenty-year Ogilvy veteran Marcia Silverman takes over as CEO, promoted from her role as president of the Americas.
Seltzer, who was formerly executive vice-president and general manager at Porter Novelli, said on his resignation: 'When I joined Ogilvy five years ago, the company was in need of a jump-start. After coming through a difficult last year, I believe Ogilvy is back on track and my work is complete.'
Silverman said she will be concentrating on developing Ogilvy's marketing offerings and is in the early stages of discussing a possible tie-up with sister ad firm Ogilvy & Mather for the Latin American region.
Silverman will hand over her role heading the Americas to Ogilvy New York director Paul Hicks.
She was previously head of Ogilvy's Washington DC office for ten years.
'Our health and corporate practices are beyond reproach, but we are not so strong in marketing and need to grow it,' added Silverman.