Margaret Rizza studied at the Royal College of Music, London and at the National School of Opera, London, and continued her training in Siena and Rome. She sang professionally for 25 years. She went on to teach singing at the Guildhall School of Music and Drama, London from 1977 to 1994. In 1986 she began her work in the field of spirituality and the wider aspect of music in the community. She has worked on many outreach projects taking groups of students to share their gifts with people in prisons and hospices etc. She also began her work with The World Community for Christian Meditation leading many retreats, prayer and music days, and vocal and choral workshops. During these years she founded and directed groups including The St Thomas Music Group and the Gaudete Ensemble which have been involved in many recordings, one of which reached the number 1 in the classical charts. She was closely involved with Dartington International Summer School up until 2008.

Margaret Rizza began composing in 1997, her contemplative choral music being published by Kevin Mayhew up until 2007. She has given many conferences featuring her music in the United States, New Zealand, Singapore, Malaysia, Ireland and the United Kingdom. In 2007 she featured in the BBC Songs of Praise programme ʻWomen Composersʼ. Harry Christophers commissioned her to write a choral composition for The Sixteen in 2007. For her this resulted in a new idiom in writing—that of classical contemporary. The composition Ave generosa came out in the recording A Motherʼs Love and was performed at the Queen Elizabeth Hall in 2008. This resulted in a collaboration with Faber Music who now publish her classical contemporary compositions. Her choral music for church choirs is published by The Royal School of Church Music.