Her family was with her when she died, Wal-Mart said.
Forbes magazine listed Walton in March as the world's 29th richest person. She died with an estimated $16.4 billion net worth. Walton was widely known in Arkansas for her philanthropy, focusing on education, the arts and families and children.
"We are so proud of our mother and the life she led," eldest son and Wal-Mart Chairman Rob Walton said.
Born Dec. 3, 1919, in Claremore, Okla., to L.S. and Hazel Carr Robson, she was a graduate of the University of Oklahoma with a finance degree. She met Sam Walton in 1942 near Tulsa, Okla., where he worked at a DuPont munitions plant.
"I just fell right in love," Sam Walton wrote in his autobiography.
They were married on Valentine's Day 1943.
The Waltons opened a Ben Franklin Stores general store in Newport, Ark., in 1945 and moved to Bentonville in 1950 after their landlord refused to renew their store lease.
They opened the first Wal-Mart in nearby Rogers, Ark., in 1962. The company now has more than 6,500 stores in 15 countries.
Besides Rob Walton, Walton is survived by son Jim Walton and daughter Alice Walton, eight grandchildren and four great-grandchildren. Another son, John Walton, was killed in 2005.