Wiedefeld attended public school through the fifth grade but completed his secondary education at Calvert Hall, a Christian Brothers school, where he received rudimentary vocal instruction and sang in several musical productions. In 1926 he was awarded a scholarship by the Peabody Conservatory of Music in Baltimore.
Upon graduation Wiedefeld found employment as a thrice-daily soloist in a Baltimore motion picture theater; he also took voice lessons with George Castelle. In 1925, Wiedefeld went to New York City, where he joined a Russian balalaika orchestra as soloist and also performed on the vaudeville circuit. In 1927 he won first prize in a National Federation of Music Clubs competition. In 1928, Wiedefeld joined the music ensemble of the Eastman Theatre Company in Rochester, N. Y. , while at the same time studying voice with Adelin Fermin at the Eastman School of Music. In 1929 he won the Caruso Memorial Foundation Scholarship, which paid for a full year of vocal training and operatic instruction under Oscar Anselmia in Milan, Italy. On returning home, he taught voice while seeking the opportunity to pursue a musical career. In 1933 Wiedefeld auditioned for Samuel L. (Roxy) Rothafel, the New York theater magnate, who engaged him as the leading baritone for his Radio City Music Hall stage productions. Roxy then persuaded Wiedefeld to adopt the name Weede for professional reasons. Weede sang at Radio City Music Hall for six years, during which time he gained widespread recognition through the venue's Sunday morning radio broadcasts. In the spring of 1937 Weede joined the Metropolitan Opera Company, for whom he debuted as Tonio in Pagliacci on May 15, 1937. Although listed on the roster of the Metropolitan for ten seasons (1937-1942, 1944-1945, 1948-1950, and 1952-1953), Weede, despite enthusiastic critical acclaim, sang but twenty-one total performances in six operatic roles for that company. When summarizing the 1940-1941 season in The Story of the Metropolitan Opera (1953), Irving Kolodin wrote, "The company would have been better served by offering more opportunities to Robert Weede, who sang an excellent Rigoletto on February 27. " Although used sparingly by the prestigious Met, Weede was in constant demand elsewhere. Beginning in the late 1930's, he sang with the Columbia Opera Company, the Baltimore Civic Opera Company, Philadelphia's La Scala Opera, the San Antonio Opera Company, the St. Louis Grand Opera Company, and three seasons with the Lyric Opera of Chicago, as well as sixty performances with the Cincinnati Summer Opera during fourteen seasons between 1939 and 1955, and 102 performances with the San Francisco Opera during sixteen seasons between 1940 and 1964. Weede also appeared in Argentina, Brazil, Cuba, and Mexico. At home he sang the male lead in the 1939 world premiere of Menotti's radio opera The Old Maid and the Thief, and he also sang in the world premiere of William Grant Still's three-act opera, Troubled Island, with the New York City Opera in 1949. In addition to his operatic engagements, Weede performed with many of the nation's leading symphony orchestras, concertized extensively, and sang at the New York Stadium Concerts, the Hollywood Bowl, Ravinia (Chicago), and Robin Hood Dell (Saratoga, N. Y. ) summer festivals. From 1942 to 1946 Weede costarred with soprano Jean Tennyson in a weekly radio program, "Great Moments in Music, " and during World War II he participated in over three dozen USO camp shows, as well as undertaking a seven-week tour of South Pacific military bases. In 1955 composer Frank Loesser engaged Weede for the male lead in his musical The Most Happy Fella, which opened in New York on May 4, 1956, and ran for 676 performances in addition to a year on tour. Weede received rare reviews in the vocally demanding role of the Italian-American vintner, Tony Esposito, while surprising many veteran theater goers with his marked dramatic talent. During the fall of 1961 Weede returned to Broadway to costar with Mimi Benzell in a 543-performance run of Milk and Honey. He then settled on the West Coast, where he served as a vocal consultant to the American Conservatory Theater in San Francisco and devoted the bulk of his time to farming and raising thoroughbred Arabian horses on the Concord, Calif. , ranch he purchased in 1962. In 1969 Weede returned to New York to portray the role of Mayor Edward Quinn in Mitch Leigh's Cry for Us All. Although the show closed after nine performances, that season Weede received a Tony nomination for best actor in a musical. Weede, an affable man of stocky build and prodigious physical strength, obtained his greatest avocational pleasure from teaching. Beginning in the early 1940's, he gave vocal instruction or operatic coaching to many of the notable singers of his day, including John Alexander, Mario Lanza, Jan Peerce, Brian Sullivan, Norman Treigle, Claramae Turner, and Earl Wrightson. During his long and diverse professional career Weede recorded for Capitol, Columbia, and RCA Victor, and was heard in live performances on three 1950 Unique Opera records: UORC 184, 200, and 295. Although he frequently sang the roles of Manfredo in The Love of Three Kings, and Scarpia in Tosca, Weede was primarily a Verdi baritone. His tour de force was Rigoletto, and Arthur Bloomfield's review of the 1940 opera season in Fifty Years of the San Francisco Opera (1972) is typical of the acclaim Weede received in that role throughout the years: "Weede was the season's new Rigoletto, his large, beautiful voice and commanding presence bringing him one of the year's bigger ovations and some of the grandest critical praise. " Weede died in Walnut Creek, California.
On November 12, 1927, Wiedefeld married Amelia Campeggi; they had two sons.