The female members of the group were called "slaves" and Raniere was known as Vanguard or sometimes Grandmaster.
The brief testimony by Lauren Salzman, one of the women present at certain meetings offered an insight into the ways in which Raniere exerted control over the women in the group, The New York Times reported.
Raniere, 58, co-founded Nxivm in the 1990s as a self-help organisation based in a suburban town in upstate New York.
"I was a slave with Keith as my master," Salzman, 42, was quoted as saying.
"I had other slaves under me."
According to the testimony, Salzman met Raniere when she was in college and began a sexual relationship with him in 2001.
But Raniere maintained sexual relationships with other women too and explained these relationships as hardships that he endured to further their personal growth.
Five Nxivm members, including Clare Bronfman, the heiress to the Seagram's liquor fortune, and Allison Mack, an actress from the TV show "Smallville", were indicted and charged last year for crimes that included identity theft, extortion, forced labour, sex trafficking, money laundering, wire fraud and obstruction of justice.
Prosecutors have alleged that Nxivm (pronounced Nex-ium) operated like a multi-level marketing pyramid scheme, and encouraged its members to continue taking pricey classes and recruiting other members in order to rise in the ranks of the organisation.