Mr. Johnson has been on a year's sabbatical in Sydney, Australia, and had planned to return to New York. The advertising network said it is eliminating the position of chief operating officer.
Mr. Johnson could not be reached immediately for comment.
"In discussing my return to TBWA's headquarters in New York it became apparent that there was not a natural fit for me in the new organization," he said in the statement.
Before his departure to Australia, Mr. Johnson had recruited Shona Seifert to replace him as president of the New York office of TBWA/Chiat/Day. He was named chief operating officer in April 2001.