Born in Budapest, Hungary and raised in Chicago, Illinois, Foldi made his professional debut in 1954, as Biondello in Vittorio Giannini's The Taming of the Shrew at Lyric Opera of Chicago. During the next two decades, Foldi established himself as a character actor of the first rank in opera houses throughout Europe and the U.S., among them La Scala, Wiener Staatsoper, Zurich Opera, Glyndebourne Opera, Cincinnati Zoo Opera and Santa Fe Opera. He created the roles of Mr. Parker in Norman Dello Joio's Blood Moon at San Francisco Opera (1961) and John W. Diller in Armin Schibler's dance-burlesque Blackwood & Co. (Das Jubliämsbett) at Zurich Opera (1962).
He made the first of his eighty-five appearances at the Metropolitan Opera in 1975, as Alberich in Das Rheingold. During his years on the roster, Foldi appeared as Schigolch in the company premieres of Alban Berg's Lulu (directed by John Dexter, 1977, which was published on DVD in 2010) and Dansker in Benjamin Britten's Billy Budd (1978) as well as playing Dr. Bartolo in the premiere of Günther Rennert's Met staging of Le Nozze di Figaro (1975). By the time his unforgettably seedy Schigolch shuffled through the Met premiere of Berg's opera, the role had become a career specialty for Foldi, who sang more than 100 performances of Lulu in San Francisco and Europe before his first New York Schigolch. Foldi continued to sing the role throughout the 1980s, with memorable appearances in Santa Fe (1980), Chicago (1987) and at the Met (1988). He was also well known for the comic part of the quack "snake oil" salesman, Dr. Dulcamara, in L'Elisir d'Amore by Gaetano Donizetti.
Foldi was also active as a teacher and as an author. In 1979, he joined the faculty of the Cleveland Institute of Music and went on to serve a decade-long tenure as the chairman and artistic director of its opera department. From 1991 until 1995, Foldi served as director of the Lyric Opera Center for American Artists; he was succeeded by Richard Pearlman. In 1999, Leyerle published "Foldi's Opera: An Accident Waiting to Happen", a collection of humorous reminiscences.
At the time of his death, he was married to Marta Justus and had two stepsons named Greg Hancock and Chris Hancock. Previously, he was married to Leona with whom he had two biological children named Nancy Foldi and David Foldi.
- "Andrew Foldi, Character Bass Who Made his Mark as Lulu's Schigolch, Has Died". Archived from the original on 18 December 2007. Retrieved 29 November 2007.