Music is taught throughout the school curriculum, up to GCSE and A-level. Scholarships are awarded annually at 11+ and Sixth Form entry and a large number of pupils receive private musical tuition across a wide range of instruments and voice. Each term many of these enter successfully for music examinations administered by the Associated Board of the Royal Schools of Music.

Music plays a very large part in the life of KGS. There are formal concerts held termly in either the Multi Purpose Hall or in the more intimate setting of the Old Hall. Progress concerts given by members of a specific year group are also given in the Old Hall to appreciative audiences of parents and friends. Each month a different group of KGS musicians performs in our series of lunchtime Coffee Concerts. The House Music Festival, held annually in the Spring Term, attracts an entry of over four hundred performers, providing an annual feast of music making. Each week students take part in the Choirs, the Orchestra or Concert Band, String Group or Swing Band. There are also a number of groups put together by the students themselves as they pursue their own individual love of music.