Kelly ter Horst was born on the 18th of January 1973 in Tegelen (Netherlands). After getting her high school diploma she went to study at the conservatory of Amsterdam, in which she enrolled in a student exchange program and temporary studied at the University of Miami. During her study she followed workshops by Edwin Rutten, Dianne Reeves & Jon Secada. Besides singing, Kelly can also play a little bit of piano & flute.

In 1996 Kelly started to sing in the girls group Mach 4, which in 1997 got chosen as best Dutch girl group of 1997. Besides that she started with studio work, like recording jingles, at Top Format in Haarlem and Jam Studio in Dallas (USA) for example. She did this for several radio stations, like: Sky Radio, Venlo FM, Omroep Brabant, Radio 5, 100% NL and Radio 10 gold. Together with Roger Happel she worked on a jingle for a Neckermann commercial, and they have also sung the jingle (Right before my eyes) for the Toyota Yaris commercial. In the meantime Kelly has worked with a lot of Dutch and Belgium artists like: Rene Froger, Allesandro Safina, Do, Sita, Xander de Buisonje, Boris, Dana Winner, Jeroen van der Boom, Candy Dulfer and Belle Perez. With these artists she has performed on stage and/or did backing vocals on their albums.

On top of all that Kelly can often be seen on television. She did backing vocals at the program X-Factor, played in the band that did "live" jingles for Giel Beelen's tv show, which was aired last summer. At "Tros Muziekfeest" Kelly regularly does backing vocals with various artists and is also seen on several dvd recordings for example Stan van Samang and Jeroen van der boom. She could also be seen on tv shows like: Top of the Pops, Barend en van Dorp and All you need is love. Kelly also writes her own songs, for example "Kijk om je heen" sung by Dana Winner, which Kelly wrote with Tjeerd van Zanen and was released as a single in the Netherlands, Belgium and Germany.
He, on his turn, wrote the song "Speed of Light" together with Bas van den Heuvel, this is one of Kelly's solo songs. Kelly has also recorded a couple of demo's with Glenn Corneille, which can be found on the music page of the website. Currently she is working on her own album, which Kelly will release herself.