The new policy applies to home office and management level associates that travel within the U.S., but not to associates who work in stores.
The company will implement a new process for verification of vaccine status for U.S. associates and continue to monitor the situation to determine if a change in its return-to-work date is necessary, according to the memo.
Walmart is also reversing its mask policy and will require all of its workers – including vaccinated ones in areas with high infection rates – to wear masks.
In stores located in areas with high infection rates, the company is encouraging customers to wear masks and will be adding back signs at the entrances.
The move comes just three days after the Centers for Disease Control and Prevention reimposed masking guidelines, recommending that even vaccinated people once again masks indoors in parts of the U.S. where the delta variant of the coronavirus is fueling infection surges.
"We continue to watch with deep concern the developments of the pandemic and the spread of variants, especially the delta variant," wrote Donna Morris, Walmart's chief people officer, in the memo circulated to employees. "We know vaccinations are our solution to drive change. We are urging you to get vaccinated and want to see many more of you vaccinated."
The Associated Press contributed to this report.