He notably created the role of Captain Dick Warrington in the world premiere of Victor Herbert's operetta Naughty Marietta in November 1910.
In Newton he began taking singing lessons with his school's music supervisor, Mrs. Gaston Boyd, who was a graduate of the New England Conservatory.
The following year he portrayed Lord Drinkwell in the original production of Julian Edwards and Stanislaus Stange's The Belle of London Town at the Lincoln Square Theatre.
[4] After appearing in several operetta productions in minor theatres and singing in cabaret performances in New York City for a few years, Harrold finally had a big break in his career when he drew the attention of Oscar Hammerstein I in 1909.
[4] In November 1910 Harrold returned to performing the operetta repertoire when he starred as Captain Dick Warrington in the first production of Victor Herbert's Naughty Marietta opposite Emma Trentini in the title role at the New York Theater.
He continued to perform in operas as well in 1911-1912 at Hammerstein's London Opera House, portraying Alfredo in Verdi's La Traviata, Arnold Melchtal in Gioachino Rossini's William Tell, the Duke of Mantua, Edgardo in Gaetano Donizetti's Lucia di Lammermoor, Ferrando in Donizetti's La favorite, Jean Grenicheux in Robert Planquette's Les cloches de Corneville, Romeo in Gounod's Roméo et Juliette, and the title role in Charles Gounod's Faust.
[1] He also performed in operas at Ravinia Park during the summer months of 1916–1919 and 1922; portraying the roles of Alfredo, Almaviva in Rossini's The Barber of Seville, Canio, Des Grieux in Jules Massenet's Manon (with Marguerite Bériza as the title heroine), Dimitri in Modest Mussorgsky's Boris Godunov, Don José in Georges Bizet's Carmen, the Duke of Mantua, Edgardo, Faust, Gerald in Léo Delibes's Lakmé, Lionel in Friedrich von Flotow's Martha, Nemorino in Donizetti's L'elisir d'amore, Pinkerton in Giacomo Puccini's Madama Butterfly, Rodolfo in Puccini's La bohème, Thaddeus in Michael William Balfe's The Bohemian Girl, Turiddu in Cavalleria Rusticana, Win-San-Lui in Franco Leoni's L’oracolo, and the title roles in The Tales of Hoffmann and L'amico Fritz.
He returned to New York City in 1914-1915 to perform with the Century Opera Company; singing the roles of Lionel, Pinkerton, Radames in Verdi's Aida, and Gounod's Romeo.
In 1918–1919 he sang with the Society of American Singers in New York City as Canio, Hoffmann, Lionel, Nanki-Poo in The Mikado, Pinkerton, Thaddeus, Turridu, and the title roles in Daniel Auber's Fra Diavolo and Reginald De Koven's Robin Hood.
He made his debut at the Met as Prince Leopold in Fromental Halévy's La Juive with Enrico Caruso as Eléazar and Rosa Ponselle as Rachel.
He sang in several United States premieres at the Met, including starring turns in Erich Wolfgang Korngold's Die tote Stadt (1921, opposite Maria Jeritza) and Nikolai Rimsky-Korsakov's The Snow Maiden (1922, as the Tsar).
In 1922 he sang opposite Madame Charles Cahier in the New York premiere of Mahler's Das Lied von der Erde under conductor Artur Bodanzky.