[1] Hadwin lives in Hesleden in County Durham; she has a brother Paul and a sister Melissa, three and four years younger, respectively.

Courtney attended Hesleden Primary School[2][3][4] and until autumn 2018 studied at The Academy at Shotton Hall in Peterlee.

[8] She also gained notice when she was filmed performing Great Big World and Christina Aguilera's soaring duet "Say Something" in September 2015 during lunchtime at her school.

[12] Hadwin performed Tina Turner's "Nutbush City Limits" in a blind audition for The Voice Kids UK.

For her final performance on 16 July 2017, she sang the torch song "And I Am Telling You I'm Not Going", from the Broadway musical Dreamgirls, before being eliminated as a finalist.

She appeared a bit shy or bashful as she walked onstage talked before singing and dancing wildly, getting the audience up on their feet.

Hadwin's performance inspired Mandel to give her a Golden Buzzer, sending her directly to the live shows.

[19][20] Hadwin returned for AGT's quarter-finals on 14 August 2018, singing "Papa's Got a Brand New Bag" by James Brown.

Although she failed to win AGT's grand prize, she went to Las Vegas to perform five live shows with winner Shin Lim at the Paris Hotel and Casino from 2–4 November 2018.

[24][25] In January 2019, she appeared as a contestant on NBC's America's Got Talent: The Champions, where she performed her first original song, "Pretty Little Thing".

[26] After her performance (when she was 14) of her original song "Pretty Little Thing" on America's Got Talent: The Champions, Hadwin's first EP was released on 25 October 2019 titled "The Cover Sessions", which includes live covers of "Sign of the Times" by Harry Styles, "Old Town Road" by Lil Nas X, "Sucker" by the Jonas Brothers, and "Someone You Loved" by Lewis Capaldi.

[34][35] During the hiatus, Hadwin released a cover of John Lennon's song "Happy Xmas (War Is Over)" on 20 November 2020 to YouTube and music streaming services.

[38] At some unknown point, she parted company with the label which inherited her account after Simon Cowell's Syco Music label ceased operations, as evidenced by a comment from Hadwin in response to a fan's (YouTube user 'Hal Dayley') comment mentioning 'Simon' on her YouTube channel post of her first music video released in 2023, 'Breakable'.