The restaurant chain, long criticized for its menu high in calories, said it had reached an agreement with the Alliance for a Healthier Generation, which was founded by the Bill, Hillary & Chelsea Clinton Foundation and the American Heart Association.
McDonald's pledged to offer and promote healthier options for a side dish, such as a salad or fruit, which would diminish its marketing emphasis on french fries. It also pledged to promote low-fat milk, juice and water to accompany meals.
The company said 100 percent of its advertising directed to children would "include a fun nutrition or children's well-being message."
The 20 markets, which include the United States, China, France, Germany, Italy, Japan, Brazil, Spain and Sweden, represent 85 percent of its global sales, the company said.
McDonald's pledged to hire an independent third party organization to monitor its progress on reaching the goals, which include rolling out healthier promotions in 30 percent to 50 percent of the 20 markets within three years and in 100 percent of them by 2020.
The agreement covers many in-store promotions, such as packaging, menu boards and posters, as well as external advertising, the company said.
The company also pledged to use in-house promotions to present child-friendly, healthier choices on various packages, such as Happy Meal boxes.
"We've seen voluntary agreements with industry have profound impact -- including our work with the beverage industry to limit the amount of calories shipped to schools. Those agreements resulted in a 90 percent reduction in total beverage calories shipped to schools between 2004 and 2010," former President Clinton said in a statement.
"If we want to curb the catastrophic economic and health implications of obesity across the world, we need more companies to follow McDonald's lead and to step up to the plate and make meaningful changes. I applaud them for doing it," Clinton said.