Saatchi's Wellington office will handle the international account when Adidas takes on the sponsorship role from July 1999 in what is one of the world's biggest sports sponsorship deals.
Adidas ousted the incumbent apparel sponsor Canterbury International Ltd last year after a three-way battle also involving rival sportsgear firm Nike International.
Financial details of the sponsorship and advertising contracts have remained confidential.
Saatchi has worked closely with the New Zealand Rugby Football Union (NZRFU) in developing its All Blacks brand, and worldwide chief executive Kevin Roberts is on the NZRFU board.
James Hall, Saatchi's Wellington managing director, said: "With Adidas, the All Blacks are set to be the next global sporting megabrand, up there with Brazil Soccer, Manchester United and Michael Jordan's Chicago Bulls."
Adidas has said it wants to take the All Blacks to a much wider global audience than before, and Saatchi said it aimed to take the brand to audiences in expanding markets like the United States, Asia, South America and central Europe.
The All Blacks have extensive national sponsorship and product endorsement in New Zealand with an official bank, snack food and soft drink.
The name and silver fern logo has also been used on numerous products, recently extended to include a men's fragrance range.
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