Credle will join the agency in October from BBDO New York, where she has worked as the executive creative director since 1995, leading the agency's M&M business.
She replaces Leo Burnett's former chief creative officer, John Condon, who left the agency earlier this year to pursue other opportunities.
Credle will oversee the creative output of Leo Burnett and Arc USA, reporting to Leo Burnett's existing worldwide chief creative officer, Mark Tutssel.