Jack Sinclair has announced he is to leave Argentine wine specialist Las Bodegas as director to assume a role at Wal-Mart.
The former managing director at Safeway will become executive vice president at the US retail giant and head up purchasing.
Des Cross is chief executive at Las Bodegas, which was established in 2004.
He said: "We are extremely proud of the fact that Jack has been appointed to such a significant position. To head up the worldwide buying of an operator of the scale of Wal-Mart is an incredible achievement.
"This is the biggest food buying job in the world and carries with it huge ethical, political and social responsibilities alongside the buying power that it wields. I am sure he will do a terrific job for them and wish him all the best in it."
Carlos Criado Perez, Las Bodegas chairman and former Safeway chief executive, will remain on the board.