In 1948 Yeend was invited by Laszlo Halasz, then artistic director of the New York City Opera, to join the roster of principal sopranos at the NYCO. She accepted and made her debut with the company as Violetta in Verdi's "La traviata" on March 20, 1948. She portrayed many other roles with the NYCO over a span of eleven consecutive seasons. Her early parts with the company were from the lyric soprano repertoire, such as Nedda, Countess Almaviva in Mozart's "The Marriage of Figaro", Marguerite in Gounod's "Faust", Micaela in Bizet's "Carmen", and the three heroines in Offenbach's "The Tales of Hoffmann". Later on in her career with the company she began portraying heavier roles from the dramatic soprano repertoire, including Amelia in Menotti's "Amelia Goes to the Ball", Eva in Wagner's "Die Meistersinger", the title role in Verdi's "Aida", the title roles in Giacomo Puccini's "Tosca" and "Turandot" among others. She also notably sang Felice in the United States premiere of Wolf Ferrari's "I quattro rusteghi" with the NYCO in 1951. Her last appearance with the company was in November 1958 as Mimi in Puccini's "La Bohème".