No reason was cited in the evening announcement by CEO Jim Skinner. A company spokesman did not immediately return a phone call seeking comment.
The company said Ralph Alvarez, president of McDonald's USA, will succeed Roberts. Alvarez will in turn be replaced by Don Thompson, currently executive vice president and chief operations officer of the U.S. business.
Roberts was widely seen as the likeliest candidate to someday succeed Skinner in the top post of the Oak Brook, Illinois-based company. After overseeing the revitalization of the U.S. business, he was promoted to the president's job in November 2004 when Skinner was named to replace the cancer-stricken Charlie Bell as chief executive. Bell died eight weeks later.
McDonald's has continued to increase sales solidly since then, although growth has recently tapered off slightly as the company came up against tougher comparisons with its impressive recent results.
"We all owe Mike a tremendous debt of gratitude," Skinner said in a statement. "Because of his leadership, our system is stronger and more aligned than ever."
Roberts, a 29-year veteran of McDonald's, could not be reached. He said in comments released by McDonald's that he was honored to have served the company and thanked owner-operators, suppliers and employees.
"As I think back over the years, I'm fortunate to have been part of so many defining moments — most recently our renaissance, which began in the U.S. in 2002 and is now occurring all around the world," he said.