Music featured throughout Joy's school life through plays, assemblies local concerts, including in Rochester Cathedral, singing at church at taking part in local talent competitions. She was a contestant in a "Star4Medway", a local talent competition promoted by the Mayor of Medway. This led to the opportunity for Joy to sing one of her own songs opening on the main stage at the Kent Music Festival at Port Lympne in 2005, where acts included Girls Aloud and Lemar.[2] Finding herself in demand within the pop world, she has regularly toured and recorded with a variety of musicians and acts since 2009 – including: Seal, Kylie Minogue, Ollie Murs, Gary Barlow, Rita Ora, Alison Moyet, Karen White, Mike Oldfield, Ronan Keeting, Hurts, Jason Donovan, Peter Andre, Izzy Bizu, Gabrielle Aplin, Ella Air and Spandau Ballet. She is currently fronting British Electronic Group, Clean Bandit for their live performances across the world.

Before starting out as a session singer, Joy performed as a member of the ACM Gospel Choir in 2006. It was an extra-curricular activity at the Academy of Contemporary Music (ACM), a music academy located in Guildford, Surrey, England. Joy, Mark De-Lisser and other ACM students featured on the BBC's talent-themed television show Last Choir Standing in 2008. The ACM Gospel Choir reached the finals of the show.

An article for Kentonline reported that Kirsten had "shared a stage with Gary Barlow, supported Girls Aloud and has sung in front of the Queen".[3] She has also worked with Producers.

She was a member of the United Kingdom national jury in the Eurovision Song Contest 2012.

In 2012, the UK version of The Voice was broadcast on BBC television and Joy took part as a solo contestant. She succeeded in the 'blind audition' round in attracting the attention of Jessie J and joined Jessie's team to compete against other teams for judges Tom and Danny O'Donoghue. At the 'battle round' stages, Jessie chose to pit Joy's talent against fellow contestant Toni Warne. Jessie chose Warne to go through but praised Joy's vocal talent.