Walton was surrounded by family members when she died of natural causes, the company said.
"We are so proud of our mother and the life she led," said Rob Walton, eldest son of Sam and Helen Walton and chairman of Wal-Mart Stores Inc. "She devoted much of her life to helping others, and to improving the quality of life in Northwest Arkansas.
"Today, my brother and sister, and the entire Walton and Robson families mourn my mother's death. But we also celebrate her extraordinary life."
Walton was born Dec. 3, 1919, in Claremore, Okla., a daughter of L.S. and Hazel Carr Robson. She graduated from the University of Oklahoma with a degree in finance.
She met the man who would become her husband, Sam Walton, a native of Kingfisher, Okla., in 1942, and the two were married on Valentine's Day 1943. Sam Walton died in 1992 at the age of 74.
After her husband fulfilled his military duties during World War II, the couple moved in 1945 to Newport, Ark., where they opened a Ben Franklin "five-and-dime" store. Five years later, they moved to Bentonville, where Sam Walton continued his career in retailing.
In 1962, the Waltons opened the first Wal-Mart in nearby Rogers. Other stores followed, and the chain grew into the largest retailer in the world but maintained its headquarters in Bentonville.
The company now has more than 6,500 stores in 15 countries.
Members of the Walton family are listed each year among the world's wealthiest people. In March, Forbes magazine listed Helen Walton as the 29th richest individual in the world, with a fortune estimated at $16.4 billion. All three of her surviving children were ahead of her on that list.
Helen Walton was widely known in Arkansas for her philanthropy, focusing on education, the arts, and families and children. She also was active in the Presbyterian Church both locally and nationally.
She was president of the Walton Family Foundation when it made a $300 million gift in 2002 to the University of Arkansas, a donation that followed an earlier $50 million grant by the foundation to the university's Sam M. Walton School of Business.
Helen Walton also set up the Walton Scholars program for the children of Wal-Mart employees, providing scholarships to 150 children annually.
She and her husband led the development of a program to bring students from Central America to three private Arkansas colleges to study. About 1,000 students have participated in the program since 1985, returning to their native countries to apply their learning and experience there.
Helen Walton is a primary supporter of the Walton Arts Center in Fayetteville. She also has been a longtime financial supporter of the University of the Ozarks, in Clarksville, and chaired the university's board.
Helen Walton is survived by sons Rob Walton and Jim Walton, and a daughter, Alice Walton, plus eight grandchildren and four great-grandchildren. Another son, John Walton, was killed in 2005 at age 58 when a homemade experimental plane he was flying crashed in Wyoming.
A memorial service is planned for Monday at First Presbyterian Church in Bentonville.