Stephenson's addition, effective March 3, will expand the retailer's board to 12 members.

Stephenson, 60, retired as AT&T's executive chairman in January this year, after a 38-year stint with the company and serving as its CEO.

He has previously served as chairman of the Business Roundtable, a group of CEOs from some of the biggest U.S. companies that Walmart chief Doug McMillon currently leads.

(Reporting by Nivedita Balu in Bengaluru; Editing by Shinjini Ganguli)