Maria Theresia Irmgard Seefried was born in Köngetried, near Mindelheim, Bavaria, Germany, the daughter of educated Austrian-born parents. She studied at Augsburg University before making her debut in Aachen as the priestess in Verdi's Aida in 1940. She began to sing the leading parts in 1942 by singing the part of Agathe in Weber's Der Freischütz in 1942, and the next year she made her debut at Vienna State Opera by singing the part of Eva in Wagner's Die Meistersinger von Nürnberg conducted by Karl Böhm. From then on, she remained with the ensemble of the Vienna State Opera until her retirement in 1976.
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 appeared at the Royal Opera House, Covent Garden in London from 1947 to 1949, and also La Scala in Milan, the Edinburgh Festival, etc. She made her Metropolitan Opera in New York City debut in November 1953 as Susanna in Mozart's The Marriage of Figaro and appeared there for only one season (1953–54), in five performances of the part of Susanna.
One of the outstanding singers to emerge immediately after the Second World War, she was noted for her Mozart and Richard Strauss roles. But she also sang in other composers' operas; the title role in Puccini's Madama Butterfly, Marie in Alban Berg's Wozzeck, Eva in Meistersinger, Blanche in Poulenc's Dialogues des Carmélites, and the title role in Janáček's Káťa Kabanová. She was also a noted lieder singer and a number of her Salzburg Festival recitals were recorded. 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, and Stravinsky.
Although she was a high soprano, she performed, and recorded, both the trousers roles of the Composer and Octavian in Richard Strauss's Ariadne auf Naxos and Der Rosenkavalier, respectively. These roles are usually associated with weightier voices and today are usually sung by mezzo-sopranos.
She often sang with Elisabeth Schwarzkopf, who said in interview that Seefried was naturally able to do effortlessly what other singers, including herself, worked all their lives to do.
After retirement, she taught students at Vienna Music Academy and Salzburg Mozarteum. She died aged 69 in Vienna in 1988.
- The Last Prima Donnas, by Lanfranco Rasponi, Alfred A Knopf, 1982. ISBN 0-394-52153-6
- Discography (Capon's Lists of Opera Recordings)
-  Irmgard Seefried 1968, on first of two acclaimed tours of Southern Africa