Johanna Embeck made her debut at the Swedish national Opera Theatre in Bollhuset in Stockholm in the 1747–48 season as the nymph Chlorix in the opera comique Syrinx by Peter Lindahl or Lars Lalin with music by Johan Ohl, opposite Elisabeth Lillström (Syrinx), Peter Lindahl (Harlequin), Petter Stenborg (Philemon), Trundman (Sylvanus) and Elisabeth Olin (Astrild).
Jean and Johanna Löfblad were the male and female star of the Stenborg Company, a status which is illustrated by their contracts, in which they are both given terms more privileged than the other members of the acting troupe but equal to each others: other than them, only Catharina Lindberg and Anders Hagendorf was given written contracts.
Petter Stenborg claimed that Jean Löfblad hid the profit "with all kinds of cunning" even though Stenborg "allowed his [Löfblad's] wife to lift her salary even during her childbirths, in accordance with the contract and in acknowledgement to her talents, but still she is just as difficult to deal with as her husband, who is even so powerful as to influence his wife..."[2] Stenborg won the case but the Löfblad couple still remained in his troupe, being the stars among his actors.
By the time the Stenborg Company finally found a permanent theater building in the Eriksbergsteatern in Stockholm in 1780, she was no longer given main parts in the plays, but was still a popular actress, now used mostly in the numerous supporting roles of old women.
When the Det besynnerliga spektaklet ('Odd Spectacle') was arranged by the dramatic Didrik Björn in the season of 1790-91, in which the actors of the theater expressed their appreciation of the audience in the shape of their most popular roles, Johanna Löfblad did so in the character of Gertrud from Njugg spar, a role she had first made in the 1784–85 season.