The former Spice Girl – now personally known as Geri Horner – has recorded the song in tribute to George Michael, who died in late 2016.
The song was supposed to be launched on BBC Radio 2 with Chris Evans, but the star is now expected on the airwaves tomorrow morning.
Evans’ show is being covered by Sara Cox today, and Halliwell tweeted: “I’m going in to @achrisevans tomorrow ( he’s not in today).xx”
Listen to Angels In Chains below.
Horner told News.com.au of the track: “I believe in times of trouble and difficult times, we find out two things: What we’re made of, and who our friends are.
“My relationship with George started out as a fan, but every time I had a little bit of difficulty he stepped up for me. When I left the Spice Girls, I went to live with him. I stayed for a long time.
“Also when I had my first child, I went to live with him. He was really sweet and kind to me.”
She added: “I’d always go around his house and play songs I was writing, asking what he’d think. Sometimes he’d tell me it was good, and sometimes he’d tell me ‘Ooh, that needs work’.
“He’d always tell me to leave space for evolution as an artist. I really admired him in so many ways.”
Geri released a single called Half Of Me in Australia in 2013 but this is her first global release as a solo artist since Desire in 2005.
She scored four consecutive Number One hits away from the Spice Girls; which was a record for a British female soloist until Rita Ora, Jess Glynne and Cheryl overtook.
Angels In Chains is out now.