The managing director role at Burnett had been vacant since last spring when Stephen Whyte was promoted to the chief executive role several months after the departure of the previous chief executive, Nick Brien.
Howe joined Leo Burnett from IMP in 1997, as an account handler on the Kellogg, Heinz Seafood and McDonald's accounts. She was appointed head of account management in 1999 and deputy managing director a year ago.
As deputy MD Howe also took responsibility for much of the agency's marketing activity following the departure of the marketing director, Clare Durwood, in 2000.
Howe will take on the day-to-day running of Burnett's London office. She will still be involved in marketing and new business. Burnett had already strengthened its management team by hiring Elliot Moss as the head of account management and Sean Kelly as the new- business director.
Howe said: "The opportunity is that the agency is in the best shape it has been in a long time and creatively is the best is has ever been and my objective is to build on this with our clients and in winning new business."