Rachel was Organ Scholar at St Paul's Cathedral in London, England from 2014-2016, and made history as the first female organist on staff in its 1400-year history. As one of the staff organists, she gave recitals and regularly played and conducted for services, working with the world-famous Cathedral Choir in the daily cycle of worship as well as services of National significance.

She combines life as a Cathedral musician with a busy international recital schedule, touring as soloist and as part of Organized Crime Duo. Recent performances have taken her to St Stephen’s Cathedral, Vienna; Wϋrzburg, Langenfeld, Essen and Recklinghausen in Germany; Hereford Cathedral; St Peter’s Cathedral, Adelaide; and St Andrew’s Cathedral, Sydney. Rachel has appeared on radio as performer and presenter, most recently accompanying the BBC Singers in Choral Evensong and presenting Inside Music on BBC radio 3 and This Is My Music on CBC radio. Rachel's debut solo album, featuring all Canadian music on the organ of Coventry Cathedral and supported by the Canada Council for the Arts, was released to excellent reviews - it received five stars in Choir and Organ Magazine and was Gramophone Magazine Editor's Choice in March 2020.

Rachel has won numerous awards and competitions in Canada, including a graduating scholarship from the Faculty of Music, University of Toronto and the Godfrey Hewitt Memorial Scholarship from the Royal Canadian College of Organists. She holds a Bachelor of Music degree in Organ Performance from the University of Toronto, where she studied with John Tuttle. Whilst pursuing her degree, Rachel was the Bevan Organ Scholar at Trinity College, Toronto, as well as the Principal Organist at Timothy Eaton Memorial Church. Once in the UK, she studied with Henry Fairs at the Royal Birmingham Conservatoire. She has also held organ scholarships at St James Cathedral, Toronto and Truro Cathedral, UK. In 2014, she was named one of the top 30 musicians under 30 in Canada by the Canadian Broadcasting Corporation.

In 2012, Rachel and fellow organist Sarah Svendsen founded the duo Organized Crime and the two organists aim to entertain audiences with their music and crazy antics. The pair have toured across Canada many times and performed in the opening concert of the Montreal Organ Festival in 2017 and at the RCCO National Convention in Halifax in 2019. For details of upcoming shows and other information, visit rachelmahon.ca.