She was the first Canadian woman record producer, initially with Boot Records for whom she produced best-selling recordings by the Canadian Brass and the guitarist Liona Boyd. In 1975 she founded Proclaim Publications to publish and record other Canadian artists, launched that year with Anton Kuerti's integral recording of the Beethoven piano sonatas on the company's Aquitaine label. The Kuerti album was followed in 1976 by three more Aquitaine releases presenting the violinist Victor Schultz, the tenor Alan Woodrow, and the cellist Gisela Depkat with the pianist Raffi Armenian. A recording taken from a 1951 recital given by Lotte Lehmann and Gwendolyn Koldofsky was released in 1977. The Canadian Children's Opera Chorus recorded Menotti's Chip and His Dog in 1979. By 1980 Aquitaine had released some 40 recordings, of which three had won Juno Awards: in 1976 Anton Kuerti's Beethoven set, in 1979 Judy Loman's performance of R. Murray Schafer'sThe Crown of Ariadne, and in 1980 Arthur Ozolins' recording of works by Stravinsky and Chopin. A second recording by Depkat and the Loman recording were awarded the Grand prix du disque by the Canadian Music Council in 1979 and 1980 respectively. The Kuerti recordings were the first of classical music to receive a Juno.
Koldofsky has worked as a film producer and director, mainly of documentaries. She has been active with many musical and community organizations both as a volunteer and professionally: The Canadian Music Competitions, the Women's Musical Club of Toronto, du Maurier Search for the Stars, the Canadian Children's Opera chorus among them.
Her writings include liner notes, poetry, newspaper columns, and work for television. Koldofsky spearheaded the efforts of the friends of Eaton Auditorium to preserve and restore that concert hall, now known as The Carlu.