Master of the King's Music (or Master of the Queen's Music, or earlier Master of the King's Musick) is a post in the Royal Household of the United Kingdom. The holder of the post originally served the monarch of England, directing the court orchestra and composing or commissioning music as required.

The post is broadly comparable to that of poet laureate. It is given to people eminent in the field of classical music; they have almost always been composers. Duties are not clearly stated, though it is generally expected the holder of the post will write music to commemorate important royal events, such as coronations, birthdays, anniversaries, marriages and deaths, and to accompany other ceremonial occasions. The individual may also act as the sovereign's adviser in musical matters. Since 2004 the appointment has been for a fixed term of ten years rather than for life, as previously.