According to Famecount.com, the rapper has almost 29 million "likes."
Gaga, who briefly held the title after unseating U.S. President Barack Obama, is less than a million behind him.
Only the late Michael Jackson has more Facebook followers, with just over 29 million.
Famecount.com bosses note that Eminem's Facebook fanbase is greater than the population of Luxembourg.
However, Gaga is still the queen of Twitter.com; she has 8.4 million followers.