The fast-food giant, which has continued to serve in the US throughout the pandemic through its pickup and drive-through sites, said it would "ask customers to wear face coverings when entering our US restaurants effective August 1."
Read the latest updates in our dedicated coronavirus section.
The requirement is consistent "with our top priority: protecting the health and well-being of our and our franchisees, employees and customers," McDonald's said in a statement.
The action comes on the heels of recent announcements by Walmart, Target and a trove of US companies that have required face coverings of customers.
More states have required masks in recent weeks as the coronavirus outbreak has spread to numerous western and southern states. But such requirements have drawn criticism from a minority of the country that has complained of having their liberty suppressed.
In early July, Texas Governor Greg Abbott issued a state-wide mask mandate after earlier resisting the move, said Friday that face masks were supported by 85 percent of voters in his state.
"We do not want to shut down again," Abbott said on CNBC. "The only way we can go about this process of not shutting down is to embrace this prospect of wearing face masks."
McDonald's said it was also holding off on reopening additional dining rooms for another 30 days.