Her death was confirmed on Saturday (6 September) in a joint statement from Reign Deer Entertainment, Robin Antin, Kemosabe Records, and RCA Records.
It read: "We are deeply saddened by the tragic news of the loss of Simone Battle of G.R.L.
"Simone was an exceptional young talent and human being, and we are all devastated to learn of her passing.
"Our thoughts and prayers are with her family and loved ones at this time."
The cause of Battle's death is not yet known.
The beautiful singer found fame with US group G.R.L. after being formed in 2013 by Robin Antin, founder of the Pussycat Dolls.
Their latest single 'Ugly Heart' is due to enter the top five of the UK's Official Chart this week.
In 2011, Simone appeared on the first series of the US X Factor, performing in front of judges including Simon Cowell and Paula Abdul.
She progressed to the live finals of the show and was mentored by Simon.
The X Factor USA have tweeted their condolences, saying: "We are greatly saddened to learn the tragic news about Simone Battle. Our hearts and prayers go out to her family and friends."
Cheryl Cole also expressed sadness with the message: "Such tragically sad news to hear of the passing of Simone battle.. My thoughts and prayers are with her loved ones #RIPSimone."
Rest in peace Simone.
Watch Simone Battle perform with her G.R.L. bandmates in the official video for 'Ugly Heart':