Doug McMillon, 47, is scheduled to take the reins Feb. 1, the company said, about four years after Duke stepped into the roles in 2009.
McMillon is chief executive of Wal-Mart International. His successor is to be announced by the end of the Bentonville, Ark., company's fiscal year Jan. 31.
Duke will stay on as chairman of the executive committee of the board and, as is traditional, will also advise McMillon for a year, Wal-Mart said. The company said Duke ultimately plans to retire.
McMillon, who first joined Wal-Mart as a summer associate at a distribution center in 1984, will immediately join the company's board.
Wal-Mart made the announcement just days before heading into
Wal-Mart's U.S. sales increased 1.6% to $202.9 billion in the nine months ended Oct. 31, compared with the same period a year earlier. International sales were up 2% to $98.8 billion.
"This leadership change comes at a time of strength and growth at Wal-Mart,"
Wal-Mart shares rose 62 cents, or less than 1%, to $80.43. During Duke's tenure, the stock has risen 90%.