He was a member of the Vienna Secession,[1][2] and associated with the Mánes Union of Fine Arts.

He remained in Vienna until 1887, although he was not an active participant in the local artistic community.

Pirner's usual themes were classical mythology (such as his Medusa (1891) and Hecate (or Hekate; 1901)) and the macabre (such as Sleepwalker (or Girl in Her Nightie Walks on the Window-Ledge; 1878), Daemon Love (1893), and Allegory of Death (1895)).

Pirner completed a number of sketches of female figures, many of them nudes.

One contemporary critic, while acknowledging Pirner's talent, considered him an "over-sophisticated mystic.