The singer, 29, posted a message on social media saying that she had inked a deal with Polydor and that it was a “pinch me moment”.
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“This is such a pinch me moment.
“I cannot wait for you guys to hear what I’ve been working on.”
Nelson left Little Mix in December after nine years, citing the toll on her mental health as the reason.
“The truth is recently being in the band has really taken a toll on my mental health. I find the constant pressure of being in a girl group and living up to expectations very hard,” she said on Instagram at the time.
"I need to spend some time with the people I love, doing things that make me happy," she went on.
The singer has carried on working on music and earlier this month defended her decision to pursue a solo music career.
Nelson said she had never said she was quitting the spotlight, simply that being in the globally successful group was too much pressure.
She told Cosmopolitan magazine: “I feel like there’s been a few people who don’t understand why I left Little Mix but am now in the studio making music. A lot of people said, ‘I thought you came out of the band to focus on your mental health?’
“I never said when I put out my statement, that I was coming out of the band to never be in the public eye, perform again or do music. I said I was coming out of the band because I genuinely couldn’t deal with the pressure of being in a girl band.”
Little Mix was formed on The X Factor 2011 after hopefuls Nelson, Jade Thirlwall, Leigh-Anne Pinnock and Perrie Edwards all originally auditioned as solo artists.
They won the competition and went on to enjoy huge success with hits such as Black Magic and Shout Out To My Ex.
After Nelson left, the remaining members confirmed they were continuing as a trio.
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