After having been widowed, Strömfelt was appointed överhovmästarinna (Mistress of the Robes) to Ulrika Eleonora of Sweden in 1736 in succession to Katarina Ebba Horn af Åminne, making her the senior of all the female courtiers, and served until the queen's death in 1741.
As such, she was the first in rank of all the female office holders of the royal household with responsibility of the ladies-in-waiting and the performance of court etiquette around them and the queen.
Upon the marriage of the crown prince to Louisa Ulrika of Prussia in 1744, she resumed her post at the court of Louisa Ulrika, and welcomed her with the rest of the late queen's court at Gnatskow in Swedish Pomerania.
As royal governess, the queen was concerned that she did not beat the children enough physically, especially the crown prince, Gustav.
She served in her two positions until her death on 8 March 1751, when she was succeeded by Ulla Tessin as Mistress of the Robes and by Ulrica Schönström as royal governess.