Chicago police spokesman Anthony Guglielmi said the suspect faces charges of aggravated criminal sexual assault, manufacturing of child pornography and dissemination of child pornography.
“Additional arrests are expected as the investigation continues,” Mr Guglielmi said, adding that more details would emerge later at a police news conference on Sunday.
Police were not aware of the alleged attack in March until the girl’s mother approached a police chief in the city as he was leaving a police station and showed him the video.
Police believe the alleged attack involved five or six males.
The girl’s mother said last month that her daughter had received online threats after the apparent attack. The Chicago Sun-Times later reported that the girl’s family had been relocated.
It is the third time in recent months that Chicago police have investigated alleged attacks broadcast live on Facebook.
In February, the fatal shooting of a two-year-old boy was captured on Facebook Live by his aunt.
In January, an attack by four people on a 19-year-old man with special needs was partially broadcast on the social media site. The four accused in the attack have pleaded not guilty.
