His decision follows last month's news that both corporate head Howard de Souza and group head of healthcare Charles Butler were to depart (PRWeek, 20 September).
De Souza left at the end of September after two-and-a-half years with Ogilvy to launch his own agency, while Butler is set to leave at the end of the year to take a career break.
May, who was unavailable for comment as PRWeek went to press, has not yet announced a date of departure or his next career move. He joined the firm in 2000.
Ogilvy global CEO Marcia Silverman said he is likely to leave by the end of the year to 'pursue other interests'.
She added it is not yet clear if he will be replaced in the role: 'I think we probably will replace him as we have a network here in Europe and need a leader.'