JoJo Siwa has addressed the rumors she stole her new song from Miley Cyrus and Brit Smith ... telling TMZ she in no way swiped the single from anyone.

We caught up with the 20-year-old outside Studio Siwa in Burbank, where she told us how she came into possession of her viral track, "Karma." As JoJo put it ... she was pitched the song -- which she defended as a very normal thing in the music industry.

She added ... "What happens is, people write songs and then they just don't do anything with them. And then, a few years later, it makes more sense for another artist."

ICYMI ... Brit's version of the song started going viral on TikTok this week after JoJo released her new music vid. Brit's take on "Karma" is reportedly from 2012, but was never officially released -- and there was even a rumor Miley recorded a demo for it too.

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JoJo confirmed the song was never another pop star's ... as "Karma" is the brainchild of the producing team Rock Mafia, who created hits for Miley, Selena Gomez and Demi Lovato, among others.

She defended ... "I didn't steal anything. There's no such thing as stealing -- I also don't know who Brit Smith is."

As for the criticism, JoJo said the song has served its purpose ... catching public attention.

JoJo is set to perform "Karma" for the first time at Miami Beach Pride Sunday ... as well as some of her other new songs.