Sophie Stebnowska was married in 1781 to the Swedish opera singer Christoffer Christian Karsten, and in 1782, she was appointed premier actress and singer of the Royal Swedish Opera in Stockholm, a position she kept for 21 years. At the wedding, the couple were given the villa Canton at Drottningholm. Though she did not reach the rank of prima donna, she was considered among the opera's most valuable members, just behind the prima donnas Elisabeth Olin and then Caroline Frederikke Müller during the 1780s and 1790s.
She was also active as a musician. In March, 1795, she participated in a public concert in Stockholm arranged by Karsten where she played the harp, while her husband and Marie Louise Marcadet sang; first each one by themselves, then jointly.
As a person, she was described by Crusenstolpe as an ideal image of the Gustavian age. She behaved according to the ideal of the Gustavian court and her movements were gracious; she was friendly towards everyone without favoring anyone; she conversed well with members of society.
By 1803, she was no longer premier actress, and in 1806, she and her husband left their positions after the temporary closure of the opera.
Gustav Löwenhielm mentions her importance in the 19th century, during a discussion about the employment of foreign artists, when he points out that several of the artists during the foundation of the Royal Swedish Opera and the Royal Dramatic Theatre had been foreigners:
"Is it impossible to engage Mr Berg and Miss Schoultz? - Generally, I can not see how we can elude the employment of halfgrown foreigners. Gustav III's Swedish national theatre started with the Danish Mrs Müller, the French Mrs Marcadet, the German Mamsell Stading, the German Mrs Augusti and the Polish Mrs Karsten. These ladies occupied our stage and kept it from the foundation of the opera and the premature departure of Mrs Olin in the beginning of the 1780s, until the year of 1800, when the school of Mrs Desguillons had created Mamsell Wässelia cum celeris."Sophie (Stebnowska) Karsten's daughter was Sophie Hedvig Karsten, premier dancer at the opera in 1805-1806, and her granddaughter was the ballerina Marie Taglioni. She died at Drottningholm.