After the early death of his father, Joseph Karl autodidactically completed his apprenticeship and began his career as a painter of miniatures, which were increasingly sought after by bourgeois circles.

After Mainz had been occupied by French revolutionary troops in 1792, Stieler followed the expelled court of Prince-Archbishop Friedrich Karl Joseph von Erthal to Aschaffenburg.

Stieler's portrait style was most especially shaped during his work in the Parisian atelier of François Gérard, a student of Jacques-Louis David.

His painted likenesses in Schloss Nymphenburg, the Schönheitengalerie, the so-called Gallery of Beauties, were commissioned by King Ludwig I of Bavaria.

Stieler accomplished this concentration through deliberate light and dark contrast, which above all highlights the accurately characterized facial features.