The Chic musician's big break as a producer came when he oversaw Sister Sledge's iconic 1979 album We Are Family and as a result he was close to the four Sledge sisters who made up the group.
Speaking to Billboard magazine about Joni's death aged 60, Nile, 64, says, "It's really heartbreaking. To me, they always felt like our younger sisters. How can they die before us, you know?"
Nile, who produced We Are Family alongside his late Chic bandmate Bernard Edwards remembers Joni as being more confident than her sisters and bandmates Kathy, Debbie and Kim.
"She was sort of like the leader of the group, the most outspoken," he explains. "Even though Kathy had that magical voice, Joni was the one who, when you ask a question she's the one who gives the answer, 'cause all four people can't speak. It would be a cacophony."
Now, 38 years on from the release of We Are Family, which included iconic hits like He's the Greatest Dancer, Lost In Music and its title track, Nile still ranks the record as one of his proudest and most important achievements.
He says, "That was the record that proved we (Nile and Bernard) could do what we do for ourselves for others, that we could look inside someone's soul and put our version of their truth onto them and superimpose it onto them and create this new entity we believed we understood. There's no filler on Sister Sledge; Every song is awesome. It was a record that was really incredible to us."
According to editors at TMZ.com, law enforcement officials believe Joni's death was due to natural causes.
Debbie and Kim Sledge have said they will honour the band's touring commitments despite their sister's death. Kathy left the group in 1989.