The Lady Marmalade hitmaker reveals the conflict dated back to the late 1960s, after Ross and her band The Supremes showed up to a joint gig at the legendary Apollo Theater in New York wearing the same gold lame outfits as Patti LaBelle and her act the Bluebelles had donned earlier that night.
She was furious at the copycat costumes, and the incident sparked a fall out with Ross which lasted almost four decades.
However, LaBelle admits the feud was all based on hearsay and her own insecurities as they had never actually spoken face-to-face.
She explains, "It was always an in and out thing. I would hear things Diana had said about me that she probably didn't, you know how people keep stuff going, and I said, 'I'm not gonna let that be', until one day... I said, 'Maybe she really doesn't like me', and we went years without seeing each other, talking on the phone or anything..."
It wasn't until 2005 that LaBelle and Ross properly met at Winfrey's Legends Ball event at her California home - and they soon realised they had no reason to fight.
During an interview on U.S. Tv show Oprah's Next Chapter, which aired on Sunday (03Nov13), she said, "We sat at the luncheon at the same table. I said, 'In all these years people are stirring (drama) around us, making me think that (you don't like me)...'
"I never wanted a rift with her because I love her talent, she's one of the best out there, and so when we exchanged phone numbers and started talking to each other after the Legends Ball... It was not cute, but I never really knew (the truth)... We're buddies now, and the thing is, it all ended well, but there was a big mess about people thinking that she didn't like me and I didn't like her; I love her."