1948 gründete er in New York die Werbeagentur Hewitt, Ogilvy, Benson & Mather, die schon bald als Ogilvy & Mather eine der international wichtigsten Agenturen wurde. ###>Ogilvy & Mather was built on David Ogilvy's principles; in particular, that the function of advertising is to sell and that successful advertising for any product is based on information about its consumer.