The singer revealed details of the track last week, when the launch of 'Nadine 2.0' was teased with a countdown to the song's release.
Written by Coyle, Damian Major and Vito Fun, 'Sweetesthigh' appears to have been made available for download on iTunes globally.
"To feel alive / I gotta catch your high / Forget the night / Just you and I, on a sweetesthigh," Coyle sings on the dance track.
Writing on Twitter, the 26-year-old told fans: "Hi beloveds, you can get 'Sweetesthigh' (one word) on i tunes almost everywhere now. I hope you enjoy our summer track we are having fun! (sic)"
Coyle has been working in the studio recently, but has not confirmed any details of a follow-up to her debut album Insatiable.
The Girls Aloud star yesterday denied magazine claims that she had branded bandmate Cheryl Cole "a failure".
> Nadine Coyle unveils 'Sweetesthigh': First Listen
Listen to a preview of Nadine Coyle's 'Sweetesthigh' below:
Nadine Coyle - Sweetest High by FreedomDevelopment