Modi's American Facebook base of 170,529 as of Wednesday is larger than all but 21 American elected officials and current candidates, the New York Times reported citing Socialbakers, a site that tracks social media accounts.
The paper attributed Modi's large Facebook fan following to the effective use of social media in his election campaign earlier this year and using it as an important part of his communication strategy once in office.
His popularity among people of Indian descent in the US was vividly displayed by the reception he got at a sold-out Madison Square Garden event here on Sunday.
The paper said that several American politicians also benefited from Modi's presence in the US.
Members of Congress who attended the Madison Square Garden event received sizable boosts on Twitter after posting pictures of themselves with the Indian leader, the NYT said.
Modi even has more American Facebook fans than Chris Christie, the Republican governor of New Jersey and potential presidential candidate, or Harry Reid, the Senate majority leader from Nevada.
Most of Modi's social media followers come from India, which has the second-largest number of Facebook users.
However, there are American politicians who have a bigger social media base outside their country.
President Barack Obama, who has more Facebook fans outside the United States (37.8 million) than inside it (15.1 million), tops the list.