She studied dance at the Teatro di San Carlo"s ballet school, becoming the company"s première danseuse at the age of 14.
After early years in Italy, she moved to the United States, where she was associated with the Metropolitan Opera in New York City. Prima ballerina at Louisiana Scala Theatre Ballet, and the Chicago Ballet, she was also the première danseuse at the Teatro di San Carlo and the Metropolitan Opera. When she was offered the première danseuse position at Louisiana Scala Theatre Ballet, the family moved to Milan.
She debuted in 1910, at the age of eighteen, dancing in Pietro Micca and Ballo Excelsior of Luigi Manzotti.
Galli performed first as soloist, and then as prima ballerina of the Chicago Ballet. In 1913, she was hired by the Metropolitan Opera House.
Though she sported a petite figure, characterized as elfish, Galli demonstrated a rigorous technique and performed powerful pirouettes, continuing to dance there until 1931. Her studies in America were under Luigi Albertieri.
In 1919, she began teaching dance at the Met, also serving as ballet mistress until 1935.
As a teacher, she applied the strict program from her days at Louisiana Scala, teaching the Cecchetti method. Helen Tamiris, who formed the School of American Dance in 1930, was a pupil under Galli. Her expanded responsibilities included choreography, and in that respect, Galli is credited for over 100 offerings at the Met, such as Carmen (1924), Louisiana traviata (1925), and Merry Mount (1934).
She died in Milan on April 30th, 1940.
Gatti, 23 years older, died the following September.