First he won a record eight gold medals at the Beijing Games.

Now Phelps is getting more than $1 million to be a spokesman for Mazda in China, the largest single sponsorship for a Western celebrity in Chinese history.

Phelps is heading back to Beijing for the first time since the summer Olympic Games. Dynamic Marketing Group's DMG Entertainment unit said in a statement that Phelps will endorse the Mazda 6 car in TV...