Rosamund Plummer began her studies at the Sydney Conservatorium High School as a student of Peter Richardson and Margaret Crawford. In 1978 she was appointed Principal Piccolo with the Elizabethan Melbourne Orchestra (now the State Orchestra of Victoria) and, a year later, Associate Principal Flute. During her time in Melbourne, she took a year's leave to study in London with Peter Lloyd of the London Symphony Orchestra and William Bennett of the English Chamber Orchestra.

As winner of the Sixth National Flute Competition in 1986, she travelled to New York to perform in masterclasses with James Galway and Louis Moyse. That same year she was appointed Principal Piccolo of the Sydney Symphony. In 1999, as the recipient of a Friends of the Sydney Symphony scholarship, she studied with Walfrid Kujala, Principal Piccolo of the Chicago Symphony Orchestra.

Rosamund Plummer also plays regularly as a guest with other Australian orchestras, including the Tasmanian and Adelaide symphony orchestras and the Australian Chamber Orchestra.

As a founding member of the flute quartet Tucana, she regularly commissions and performs new music by Australian composers. Rosamund Plummer is a part-time lecturer in flute at the Sydney Conservatorium of Music, and co-author of Studies for the Advanced Flautist (Australian Music Centre).