Anna Maria Dell'Oso was born of Italian parents and, after studying Arts and Social Work at the University of Melbourne, transferred to the Victorian College of the Arts to study violin. She also studied briefly at the Tasmanian Conservatorium before travelling to New Zealand where she trained as a journalist for the Christchurch Star. In 1978 she joined the Sydney Morning Herald and subsequently worked for a number of Sydney newspapers and magazines as a columnist, and feature writer and as a film critic for ABC TV. She also studied screenwriting at the Australian Film and Television School. Her work has been read on Radio 2EA in 1989, on SBS TV in 1990 and on ABC Radio. She has read at Sydney University (1985), at the Harold Park Hotel, Sydney (from 1986) and for various student and teacher groups.
Dell'Oso's involvement in theatre began by default, when fellow journalist, Sally White (who had herself written a libretto with English composer Nicola Lefanou), could not undertake a collaborative project with composer Gillian Whitehead due to her pregnancy. Unsure of her ability as a librettist Dell'oso undertook a course in playwriting at NIDA for a year, and subsequently the first Whitehead/Dell'Oso project, The Pirate Moon was completed and then stage by students of New Zealand Opera School in 1986. Several years later Whitehead was commissioned by the Festival of Perth to write an opera. The result was the Whitehead/Dell'oso collaboration Bride of Fortune, which after a few years delay was eventually staged for the festival in 1991. This opera, which sees the story shift from Italy to Australia, was undertaken with a good deal of empathy not only from Dell'oso, whose Italian background made her an obvious choice to write the libretto, but also from Whitehead, who had previously lived in the country, and who therefore understood implicitly what her librettist was after.
Following the completion of Bride of Fortune Dell'oso began working on several projects, including a biography on one of her former music teachers, Jan Sedivka, and two novels - one about a search for a precious centuries-old Panormo violin, and the other about Aboriginal adoptions. She has also worked with Monica Pellizzari on a film about an Italian princess who falls in love with a married man, and is thus banished to a remote village.