Katarzyna Magdalena Rooijens (née Szczot; born 5 November 1967 in Warsaw), professionally known as Kayah, is a Polish singer-songwriter performing a variety of music genres, including pop, soul, jazz, world and dance. She has also experimented with disco, funk, electronica as well as Balkan and Jewish music.

Kayah released her first self-written album in 1995 and has since established herself as one of the most critically and commercially successful Polish singers. She is one of the most awarded artists by the Polish Society of the Phonographic Industry (ZPAV) and has placed fourth on Polish music magazine Machina's list of "50 best Polish female singers". Kayah has sold over one million records in Poland and most of her albums have been certified platinum or gold by ZPAV. Particularly successful was the 1999 collaborative album Kayah i Bregović, recorded with Yugoslav musician Goran Bregović, which was certified diamond for selling over 700,000 copies, and spawned hit singles "Śpij kochanie, śpij" and "Prawy do lewego". Her other hits include "Fleciki", "Na językach", "Supermenka", "Testosteron", "Prócz ciebie, nic" with Polish singer Krzysztof Kiljański and "Po co" with Israeli musician Idan Raichel. She has also collaborated with Cape Verdean singer Cesária Évora.

In the early 2000s, Kayah co-founded her own record label, Kayax, which has since signed many successful artists and released numerous critically acclaimed albums. She has also hosted a number of television and radio shows and occasionally appeared in TV series and films in Poland. Kayah has also been outspoken politically, having supported Poland's Women's Party and the Committee for the Defence of Democracy. She is also an ally and supporter of the Polish LGBT community.