She made her debut on stage in
Little Eyolf by
Henrik Ibsen which was directed by Esser on 5 November 1897. Royaards-Sandberg went on to make her first professional stage appearance playing the part of Emilia in
William Shakespeare's ''
The Winter's Tale at the on 15 November 1901 and also was cast as Sanderijn in Lanseloet van Denemerken'' De Duecht' in
Elckerlijc in 1908. Between 1908 and 1924, Royaards-Sandberg featured in plays that were directed by her husband . She was cast in the role of Eve in the play by
Joost van den Vondel on multiple occasions. Royaards-Sandberg also had roles as Rafaël in Vondel's
Lucifer in 1910 as well as Badeloch in
Gijsbreght van Aemstel between 1911 and 1912 by the same playwright. She was cast in the role of
Olivia in Shakespeare's
Twelfth Night between 1916 and 1917 and Greetje in
Johann Wolfgang von Goethe's ''
Goethe's Faust'' from 1917 to 1918. Following the death of her husband in 1929, Royaards-Sandberg and others established the Nieuwe Schouwtooneel company. She went on to work with the Het Masker, the Amsterdam Theater Company, the Dutch Comedy, Theater, Ensemble and the Amsterdam Toneel. She declined to register for the
Nederlandsche Kultuurkamer during the
Second World War but she would return to stage acting following the war. In 1955, Royaards-Sandberg setup the theater group Test with Kees van Iersel and and it performed experimental theatre following regular performances. When she was 80 years old, she was cast as Esther Crampton in
Home, sweet home by
Paul Osborn for the 1956–1957 theatre season. A decade later, Royaards-Sandberg played the role of the grandmother in
Federico García Lorca's
The House of Bernarda Alba. Following her receiving the silver medal from the city of Amsterdam in 1967, she sustained a fall at her home two years later, which restricted her movement but she had a role in
The Loves of Cass McGuire by
Brian Friel in 1972. Royaards-Sandberg published her memoirs,
Herinneringen in 1972. ==Personal life==