Stewart takes up the position from today (1 September), replacing Stuart McCullough, who left the business by mutual consent. His responsibilities include marketing, branded goods, and global sales and after-sales.
He rejoins Bentley following a six-year absence during which he occupied roles within Volkswagen Group, including heading up marketing across its luxury marques, including Lamborghini. He most recently held the position of board member for sales, marketing and customer service at sports car brand Bugatti.
The marketer began his career in the automotive sector at Toyota, before joining Rolls Royce Bentley Motor Cars in the 1990s and, eventually, becoming regional director for Bentley North America.
Franz-Josef Paefgen, Bentley Motors chief executive, said: "It is a pleasure to welcome Alasdair back to the Bentley family. Having worked with him at Bugatti, I know he has the necessary experience, ability and enthusiasm for the high luxury automotive sector, to which can be added his undoubted knowledge of the Bentley brand."