A true polymath, Heinrich Lefler worked as a painter, graphic artist and stage designer. He was a founding member of the "Hagenbund", a collective of artists at odds with the conservative Vienna Künstlerhaus, which operated in the shadow of the more popular Vienna Secession. From 1900-1903 he was assistant to Anton Brioschi, head designer at the Vienna State Opera, where he designed a set for the Metropolitan Opera in New York. He held a professorship at the Academy of Fine Arts Vienna from 1904-1910.
Lefler collaborated with his Brother-in-law, the scenic designer Joseph Urban, painting murals and designing invitations. The team also designed public events, festivals, and theatrical performances. Many of Lefler's costumes and stage designs have been preserved in the Max Reinhardt Collection at Harvard.
As a graphic artist and designer, Heinrich designed banknotes, promotional posters, and financial warrants. In 1903 he was awarded the design of the 1000 Kronen banknote. The banknote features a portrait of his wife, opera singer Mina Wiesmüller.