Poell was born in Linz, Austria and studied medicine at the University of Innsbruck and obtained his doctorate there.
He then turned to vocal studies at the Vienna Music Academy with Philip Forsten and Joseph von Manowarda.
He made his operatic debut at the Deutsche Oper am Rhein in Düsseldorf in 1929, where he sang for ten years and where he took part in the premiere of Ludwig Maurick's work Simplicius Simplicissimus, on 23 March 1938.
He made guest appearances at La Scala in Milan, the Royal Opera House in London.
His performance in 1950 of Bach's Mass in B minor conducted by Herbert von Karajan, alongside Elisabeth Schwarzkopf, Kathleen Ferrier, Walther Ludwig and Paul Schöffler, was recorded live.