Kousay Mahdi was born in Baghdad in 1966 into a family of musicians. He began his musical studies in his native country before continuing, from 1985, in Budapest at the Béla Bartók Conservatory as a student of Ottó Kertész. In 1988 he was admitted to the Liszt Ferenc Academy of Music, where he studied under László Mező and Ferenc Rados. He won second prize at the David Popper Cello Competition in 1992. A year later, in 1993, he joined the Hungarian Radio Symphony Orchestra. Since then, he has been a regular performer not only on the Hungarian concert scene but also abroad. Among other groups, he is a member of the Pulzus Quartet, the Budapest Cello Ensemble and the Trio da Capo. He received the Artisjus Prize in 2003 as a member of the Budapest Cello Ensemble. Kousay Mahdi has been a member of the Budapest Festival Orchestra since 2008. He has recorded several solo CDs for Hungaroton.