Sally Beamish was born in London. She studied viola at the RNCM with Patrick Ireland and in Detmold with Bruno Giuranna and was a founder member of the Raphael Ensemble. In her early career, Beamish performed regularly with the Academy of St Martin-in-the-Fields and the London Sinfonietta and was principal viola in the London Mozart Players and Scottish Chamber Orchestra.

In 1990, she moved from London to Scotland to develop her career as a composer. Her music embraces many influences - particularly jazz and Scottish traditional music.

She has recently moved to Brighton and is married to writer Peter Thomson. She still performs regularly as violist, pianist and narrator.

In February 2012 and July 2015, Beamish was BBC Radio 3 Composer of the Week.

Her ballet, The Tempest (for Birmingham Royal Ballet and Houston Ballet with choreographer Sir David Bintley), was premiered in October 2016 at Birmingham Hippodrome and Sadler's Wells, London, with the US premiere by Houston Ballet in May 2017.

Her second ballet, The Little Mermaid (choreographer David Nixon OBE), was premiered in September 2017 by Northern Ballet and toured the UK with 75 performances. It will tour the UK again in Autumn 2022.

In 2018, she was a featured composer at the Ryedale and Trondheim festivals, performing with the Orchestra of the Age of Enlightenment as narrator and with the Elias and Chilingirian Quartets on viola, as well as several appearances as pianist.

From 2018-2020, Beamish was composer-in-residence with the Academy of St Martin-in-the-Fields for which she wrote Partita for string quartet and Hover for oboes, horns and string orchestra which was featured at the Academy's 60th anniversary gala concert at London’s Queen Elizabeth Hall in November 2019.