She graduated from the Fryderyk Chopin Secondary School of Music in Bytom in the cello and piano classes. She is a graduate of the Faculty of Jazz and Popular Music in the vocal class of the Karol Szymanowski Academy of Music in Katowice. Initially she sang under the supervision of Elżbieta Chlebek. She released her first demo in 2002. The song was heard by Robert Janson, the founder of Varius Manx. As a result of cooperation with Janson, Moś recorded the single I Wanna Know, with which she took part in the national qualifiers for the 2006 Eurovision Song Contest. In 2008–2011 Kasia Moś lived in the United States, where she performed, among others, at the Viper Room club. In 2012, she took part in “Must Be the Music” show on Polsat, where she won third place. Kasia Moś has recorded one studio album. In 2015, she released the album Inspiration, containing the single Addiction. In 2017, she won the national qualifiers for the Eurovision Song Contest with the song Flashlight.