Dillon studied voice at Mount Holyoke College and with baritone Francesco Mottino in Milan.
She had a prolific career as a dramatic soprano in Europe during the first decade and a half of the 20th century, giving more than 1,800 opera performances.
She was especially active in Italy and sang at most of the principle houses in that country, including La Scala.
[3] Dillon abandoned her singing career shortly before the outbreak of World War I; largely due to continual bouts with illness.
Among her notable pupils were Richard Crooks, Marie Sundelius, Kathryn Meisle, and Frederick Jagel, and musical theatre actress Evelyn Herbert.