Ronan has developed a formidable reputation as a composer in the world of contemporary jazz, and his music has been performed by such luminaries as Dave Liebman, Kenny Werner, Kenny Wheeler, Keith Copeland, John Abercrombie, Andy Laster, Simon Nabatov, Richie Beirach, Tom Rainey, Julian Arguelles, Rick Peckham and Sonny Fortune.

He is equally respected in the world of contemporary classical music and has made a speciality of writing for mixed ensembles of jazz and classical musicians. Since 1993 Ronan has been composing for classical ensembles - writing compositions which feature both improvised and written music. He has had great success in this field and now has a large body of work that ranges from solo piano pieces, to chamber works, to orchestral compositions. He has had commissions from a wide range of ensembles and organisations including the RTE Concert Orchestra in Dublin, The Opus 20 String Orchestra in London, and the European Jazz Youth Orchestra. He has also been commissioned to write works for many great soloists including the saxophonist David Liebman, the violinist Michael D'arcy and the virtuoso accordionist Dermot Dunne.

The following are a selection of bodies and musical groups who have commissioned Ronan to write music for them:

The Contemporary Music Centre

RTE Concert Orchestra

Jazz On the Terrace

National Concert Hall

Opus 20 String Orchestra

Dublin Jazz Festival

Dun Laoghaire Rathdown County Council

Boyle Arts Festival

Improvised Music Company