Maria Theresia Irmgard Seefried was born in Köngetried [Wikidata], near Mindelheim, Bavaria, Germany, the daughter of educated Austrian-born parents.

She began to sing leading parts in 1942 (Agathe in Weber's Der Freischütz in 1942, and the next year she made her debut at Vienna State Opera with Eva in Wagner's Die Meistersinger von Nürnberg conducted by Karl Böhm).

She sang at the Salzburg Festival every year from 1946 to 1964 (except 1955, 1961 and 1962) in operas (Susanna in The Marriage of Figaro, Fiordiligi in Così fan tutte, Zerlina in Don Giovanni, Pamina in The Magic Flute, Marzelline in Fidelio and the Composer in Ariadne auf Naxos), concerts and recitals.

She left many recordings of oratorio and sacred music by Bach, Mozart, Haydn (including at least four different renditions of the Archangel Gabriel in Die Schöpfung), Brahms, Fauré, Beethoven, Dvořák, Verdi and Stravinsky.

Although she was a high soprano, she performed, and recorded, both the trouser roles of the Composer and Octavian in Richard Strauss's Ariadne auf Naxos and Der Rosenkavalier, respectively.