Marchesi was born in Frankfurt. Her father's last name was Graumann; her aunt was the pianist and friend of Beethoven, Dorothea von Ertmann (née Graumann). In her adolescence her family fortunes failed, so she travelled at the age of 22 to Vienna to study voice. Thereafter she went to Paris and studied with Manuel García II, who was to have the foremost influence on her. She made her debut as a singer in 1844, and had a short career in opera and recital. Her voice, however, was only adequate, so she moved to teaching in 1849. In 1852, she married Italian baritone Salvatore Marchesi (pseudonym of Salvatore de Castrone della Rajata) (d. 1908).