The singer didn't reveal when the awkward moment took place, but revealed she "didn't realise" at first as she took the incident in her stride.
Asked about her "most embarrassing" on stage experience, she told 'Smallzy's Celebrity Small Talk': "My top came off! I'm not gonna tell you which show...
"There was two layers, but the mesh top underneath was no bra, see through. But then the one on top - it's like a belt - and it ripped off!
"I didn't realise until I looked down, I was like, 'Oh, nipple!' "
She also revealed how star-struck she was getting to meet The Jonas Brothers when she was younger.
She gushed: "Oh my God, The Jonas Brothers, at Wembley stadium. They come towards me in synchronicity, they were walking exactly the same - and I think they had wind blowing up into their hair.
"I was like, 'What is going on right now?' This was the early 2000s, but it was literally them."
Meanwhile, Ava has been celebrating after hit single 'Sweet But Psycho' - which featured on her debut album 'Heaven & Hell' surpassed one billion Spotify streams.
Reflecting on the track's incredible success, she said: "It's insanity... I'm freaking out internally. It's crazy, I just can't believe this. After, what, two and a half years? I feel like [it's] such a milestone. The fans did that.
And the star credited her passionate fanbase for the song's popularity, and how it changed her career.
She added: "Remember, that was out of nowhere - no one knew me before 'Sweet But Psycho'. That song just took its own life."