The daughter of a famous dancer, Platon Karsavin, she was educated at the Imperial Ballet School, St. Petersburg, under such teachers as Cecchetti, Christian Johansson, and Paul Gerdt, graduating in 1902. As ballerina at the Mariinsky Theatre she included in her repertoire Giselle and Odette-Odile in Swan Lake. Karsavina is best known as the leading ballerina of Sergey Diaghilev's Ballets Russes from its beginning in 1909 until 1922. Between 1909 and 1914 (paired with Nijinsky until 1913) she created the majority of famous roles in Fokine's Neoromantic repertoire, including Les Sylphides, Le Spectre de la Rose, Carnaval, Firebird, Petrushka, and Thamar. She also created leading roles in Léonide Massine's The Three-Cornered Hat and Pulcinella. She came out of semiretirement in the early 1930s to revive some of her more famous roles for the Ballet Rambert and to create new ones for Frederick Ashton.

After marrying the English diplomat Henry James Bruce, Karsavina went to London (1918), where she helped found the Royal Academy of Dancing (1920), for which she organized the Teachers' Training Course and the Camargo Society (1930). She also coached Margot Fonteyn. Her writings include articles on technique for the journal Dancing Times, her autobiography Theatre Street (1930), and the text Classical Ballet: The Flow of Movement (1962).