Irmgard Seefried was born in Köngetried, near Mindelheim, Bavaria, Germany. She studied at Augsburg University. Her first appearance in opera was in Aachen where she sang the role of the priestess in Verdi's Aida in 1940. She soon began to sing leading parts, and in 1943 she sang the part of Eva in Wagner's Die Meistersinger von Nürnberg at the Vienna State Opera conducted by Karl Böhm. Since then, she belonged to the ensemble of the Vienna State Opera until she retired in 1976.
She sang at the Salzburg Festival nearly every year and gave many recitals. She appeared at the Royal Opera House of Covent Garden in London from 1947 to 1949, and also La Scala in Milan, Edinburgh Festival, etc. She sang at the Metropolitan Opera in New York during the 1953 -a1954 season the role of Susanna in Mozart's The Marriage of Figaro
She is especially remembered for her singing of the music of Mozart and Richard Strauss, but she also sang in other composers' operas; the title role in Puccini's Madama Butterfly, Marie in Alban Berg's Wozzeck, Eva in Der Meistersinger von Nürnberg, Blanche in Poulenc's Dialogues des Carmélites, and the title role in Janáček's Káťa Kabanová. She was a great lieder singer and several 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 performances of the Angel Gabriel in Die Schöpfung), Brahms, Fauré, Beethoven, Dvořák, and Stravinsky.
She often sang with Elisabeth Schwarzkopf, who said in an interview that Seefried could do easily some things which other singers struggled all their lives to do.
She was married to the Austrian violinist Wolfgang Schneiderhan from 1948 until her death.
After retirement, she taught students at Vienna Music Academy and Salzburg Mozarteum. She died aged 69 in Vienna in 1988.