The mask requirement applies to both Apple employees and customers, according to the company. The policy change surfaced amid rising concerns about the omicron COVID-19 variant, which is thought to be highly contagious and capable of evading some protection provided by existing vaccines.
"We regularly monitor conditions, and we will adjust our health measures in stores to support the wellbeing of customers and employees," Apple said in a statement. "Amid rising cases in many communities, we now require that all customers join our team members in wearing masks while visiting our stores."
Apple has repeatedly altered its in-store mask policies in response to COVID-19 cases levels. In November, the iPhone maker eased mask requirements in roughly half of its U.S. stores as case numbers declined.
States are also reconsidering their mask policies in response to the omicron variant. California and New York have reinstated indoor mask mandates in recent days.