Kirkby did not originally intend to become a professional singer. In the late 1960s, while she was studying classics at Oxford, she joined the Schola Cantorum of Oxford, a student choir which, at the time, was being conducted by Andrew Parrott. After graduation, Kirkby went to work as a school teacher, but became increasingly involved in singing with the growing number of music ensembles that were being founded during the Early music revival of the early 1970s. She married Parrott, and sang with his Taverner Choir which he founded in 1973. Her vocal career developed throughout the 1970s, and she became noted as a soloist in performances and recordings with prominent early music performers, including Anthony Rooley and the Consort of Musicke and Christopher Hogwood's Academy of Ancient Music.