The CEOs of Walmart and its Sam's Club wholesale stores made the announcement in a statement Friday.
"We will begin requiring that associates wear masks or other face coverings at work. This includes our stores, clubs, distribution and fulfillment centers, as well as in our corporate offices," it said.
Customers will also be encouraged to cover their faces, although it will not be mandatory. Walmart will provide all employees with a face covering, or they can bring their own.
"We hope this step will promote safety and consistency across all of our facilities and be of comfort to our customers and members. However, it's important to remember that face coverings are simply an additional health precaution. They do not guarantee against the spread of this virus," the statement said.
Workers at grocery stores and warehouses deemed "essential businesses" amid the Covid-19 outbreak have expressed concern that showing up to work puts them at risk of contracting the disease. Just this month, two workers at a Chicago-area Walmart store died from the coronavirus.
In recent weeks, a number of retailers have said they will provide workers with masks, but sourcing such protective equipment has proved difficult as hospitals and health workers also struggle to get their hands on such gear.
Walmart, the largest private employer in the United States, has waited to secure protective gear to avoid limiting equipment that could go to strained health workers, Dan Bartlett, the company's vice president of corporate affairs, previously told reporters. The company will need more than seven million masks each week for its employees, he said.
The company has also reduced the number of customers who can enter stores at one time, using floor markers to enforce social distancing and establishing designated entrance and exit doors. Walmart previously announced measures including paid leave for workers amid the coronavirus outbreak, employee temperature checks and limited store hours to allow for cleaning and restocking.