Lisa Illean is a composer of acoustic and acousmatic music, based in the U.K. Her music has been described as "exquisitely quiet shadows shaded with microtunings" (The Sydney Morning Herald) and "a compelling exercise in stillness and quietude" (The Australian). Illean's work spans pieces written for orchestra to those commissioned for new, prepared or adapted instruments, and sound works conceived for unique spaces. This has led to her presenting music around the globe, including at Festival Présences (Paris), Donaueschinger Musiktage, Wittener Tage für neue Kammermusik, Time:Spans (New York), Taiwan International Festival of Arts, the BBC Proms, Unerhörte Musik (Berlin), Angelica Festival (Bologna), Huddersfield Contemporary Music Festival, Tzlil Meudcan (Tel Aviv), Transit Festival (Leuven) and November Music (S'Hertogenbosch), in venues ranging from Elbphilharmonie (Hamburg) to the industrial bays of Sydney's Carriageworks and London's Café Oto. Lisa teaches at the University of Cambridge and was Composer-in-Residence at the Royal Academy of Music in 2021-2022.

Many of Illean's compositions arise out of working with non-tempered tuning systems, playing close attention to sonority, subtly unfolding harmonic forms, auditory phenomena and perspective. In recent years she has oriented her practice as a composer to include making long-form pieces with both performed and pre-recorded material, in close development with one or two others. This process incorporates unadorned, 'everyday' instruments—often simply-made zithers; exploring visual analogies and tactile ways of sketching. She has also made a number of pieces for voice, including A though-grown earth (2018) for Juliet Fraser and Sleeplessness ... Sails (2018) for Sarah Connolly. Cantor, for soprano and ensemble, was named Instrumental Work of the Year at the 2018 Australian Art Music Awards.  

Premiered in 2017 by members of the Philharmonia, Januaries for ensemble has since been programmed by seven other ensembles in the U.K., U.S. and Australia. Land’s End, premiered by the Sydney Symphony Orchestra and David Robertson, has been taken up by the BBC Symphony Orchestra, Adelaide Symphony Orchestra and the orchestra of the Australian National Academy of Music.

She has been commissioned by Ensemble Intercontemporain (ever-weaver), London Sinfonietta (Tiding), Donaueschinger Musiktage (Tiding II), Explore Ensemble (ensemble version of A through grown earth), and Ukaria Cultural Centre: a new work for the musicians of Australian National Academy of Music and Aura Go. Her music has recently been performed by the Adelaide Symphony Orchestra, Melbourne Symphony Orchestra, London Sinfonietta, Psappha, Explore Ensemble, Trio Accanto, and Juliet Fraser. Her 2021 piece Tiding has already been programmed by guitarists such as Huw Davies, Yaron Deutsch, Sean Shibe and Sam Cave.