He made his debut at the Aix-en-Provence Festival in 1950 singing Ottavio in Don Giovanni and Ferrando in Così fan tutte.
He took part in the revival of opera such as Rameau's Les Indes galantes and Orphée in the French version for tenor of Gluck's Orfeo ed Euridice.
In France he was frequently singing opposite his wife, who was a light lyric coloratura soprano excelling in the same repertoire as her husband.
Simoneau also sang the role of Belmonte in Sir Thomas Beecham's recording of Mozart's Die Entführung aus dem Serail, and the role of Ferrando in Mozart's Così fan tutte opposite Elisabeth Schwarzkopf, Nan Merriman, Rolando Panerai, Lisa Otto, Sesto Bruscantini, conducted by Herbert von Karajan, both considered classics.
Simoneau made his debut at the Lyric Opera of Chicago in 1954, he sang there until 1961, notably in Verdi's La traviata opposite Maria Callas.