The West Derby musician won the event playing Carl Neilsen's Clarinet Concerto with the Northern Sinfonia in the final in Gateshead, England, on Saturday, May 20.
Simpson is principal clarinet of the National Youth Orchestra and hopes to study clarinet and composition at music college.
Judges included Marin Alsop, principal conductor of the Bournemouth Symphony Orchestra, and pianist Angela Hewitt.
Other finalists included guitarist David Massey, who performed Rodrigo's Fantas‹a para un gentilhombre; percussionist Toby Kearney playing James MacMillan's Veni Veni Emmanuel; trumpeter Huw Morgan performing Henri Tomasi's Trumpet Concerto; and Cordelia Williams, who performed Saint-SaêŠns' Piano Concerto No. 2.
The popular biennial event is broadcast on BBC television. It was established in 1978 by Humphrey Burton and the late Walter Todds of BBC Television's music department. Previous winners include Nicola Benedetti, Stephen Hough, Barry Douglas, Emma Johnson, and Tasmin Little.