In 1905, he debuted with Ung sorg (Young sorrow) and Kvæde (Songs), collections of poetry, followed by Sollaug in 1908, and Villfuglar (Wild birds) in 1909.

With the short-stories collection Ved Akerselva (By the Aker River) in 1910, Uppdal introduced his epic 10-volume series of novels, Dansen gjenom skuggeheimen (The Dance through the Shadow Land).

Two of the volumes were republished in revised editions in the 1950s, in which Uppdal (in addition to expanding the narrative considerably, and emphasizing the political agenda) had changed the language used into a more archaic and dialectal form.

Uppdal was finally granted a poet's pension by the state in 1939, perhaps due to his long periods of financial hardship.

When confronted with his difficult prose and asked if he had plans to make his novels more audience-friendly, he is said to have responded: "I don't give a damn about the audience!