The study by the Washington, DC-based think tank concluded that Muslims were the fastest-growing major religious group in the world and would account for up to 30 percent of the global population by 2050.
There were 1.6 billion Muslims living in the world in 2010, which made up just over 23 percent of the global population, according to the Pew Research Center.
The percentage of Christians was projected to remain unchanged at just over 31 percent in 2050.
The report also said that Islam was set to overtake Judaism as the second-largest religion in the United States by mid-century.
The Pew Research Center study used data from 198 countries and territories on fertility, age composition and life expectancy, as well as rates of religious switching and migration between countries.