Dame Gillian Weir was born in Martinborough before moving to Whanganui. At 19 she was co-winner of the Auckland Star Piano Competition, and shortly afterward she left for England after having won a scholarship from the Associated Board of the Royal Schools of Music in London. In her second year there (1964) she won the prestigious St. Albans International Organ Competition. Her performance on this occasion was a work by Messiaen. She became particularly associated with this composer, performing his complete works several times, and her recording for Collins Classics has been hailed as 'one of the major recording triumphs of the century'.

Alongside her music Weir often shared her knowledge as adjudicator for leading international competitions, as well as working as a lecturer, broadcaster, teacher and writer. Her series of recitals in Westminster Cathedral of Messiaen's organ works in 1998 attracted huge audiences. For these, she was awarded The Evening Standard Award for Outstanding Solo Performance, the first organist to have been so honoured.

Her numerous awards and accolades include 1989 Queen’s Birthday Honours and Dame Commander of the British Empire in 1996. She was named by Classic CD magazine as one of the 100 greatest players of the century and by the Sunday Times as one of the 1000 music makers of the millennium. She has also served as the first woman President of the Incorporated Society of Musicians, the Royal College of Organists and the Incorporated Society of Organists. She is also the Prince Consort Professor of Organ, Royal College of Music, London. Over her career, she has made over 350 concerto appearances with many of the world's greatest orchestras.