The 22-year-old rapper, whose real name is Daniel Hernandez, was one of four people taken into custody Sunday.
The arrests appear to be connected to a shooting at a party last month on the Upper East Side.
Among those arrested are the victim, Faheem “Crippy” Walter, who was shot during the fight, and Tekashi69’s recently-fired former manager, 36-year-old Kifano “Shotti” Jordan. Jensel “Ish” Butler was also arrested.
They are all charged with racketeering and firearms possession.
The rapper, also known as Tekashi 6ix9ine, has been one of the most ascendant and controversial names in hip-hop in recent months. His debut album, Day69, was among the most downloaded records on iTunes following its February release.
But he also has had a series of run-ins with law enforcement and has publicly identified himself as a member of a violent New York gang. He recently pleaded guilty to disorderly conduct in Brooklyn Criminal Court in connection with a May traffic stop.
In a 2015 case in New York, 6ix9ine was sentenced to probation for his involvement in a sexually explicit video of a 13-year-old girl.
The video, posted on social media, showed the girl performing a sex act on another man while 6ix9ine “stands behind the child making a thrusting motion with his pelvis and smacking her on her buttocks,” according to court documents.
The shooting occurred outside what was a party to celebrate Tekashi69 receiving probation in that child sex case earlier in the day.