He achieved some success almost immediately on graduating, winning the competition for the design of the pedestal for the memorial bust to commemorate the architect Carl Ludwig Engel – but it was never realised.

In 1892, soon after returning to Finland, he was appointed assistant lecturer at the Polytechnic Institute (founded 1879), where he himself had previously been a student, a position he held for the rest of his life, and where the head of the school at the time was Gustaf Nyström.

Nyström had contributed to the journal Suomen Teollisuuslehti (Finnish Industrial Magazine) edited by his architecture partner Vilho Penttilä.

[2][4] Usko Nystöm established a joint architectural form with Albert Petrelius (1865–1946) and Vilho Penttilä (1868–1918) in 1895 and the partnership continued until 1908.

Albert Petrelius was both an architect and master builder and as well as being a partner in the architectural form also simultaneously worked for a fire insurance company, while the architect Vilho Penttilä was also editor-in-chief of the journal Suomen Teollisuuslehti (Finnish Industrial Magazine), and which provided an outlet for showing the works of the architectural firm.

Petrelius and Penttilä were members of the pro-Finnish language and pro-Independence Fennoman movement (at that time the vast majority of architects were Swedish-speaking).

Historian Eija Rauske suggests that models for the designs of the apartment blocks came from the major cities of central Europe, and in particular Paris and Vienna.

The Wuorinen apartment building is a 5-storey (plus attic storey) neo-Renaissance style building taking up an entire city block, with heavily rusticated ground floor (containing shops) and heavy roof cornice; the finesse of the facades is supposedly picked out in the exposed brickwork on the upper floors and plaster-cast emblems of various forms, in particular the letter W, referring to the client of the project.

By contrast, the Schalin apartment building at Kapteeninkatu 11 – Tehtaankatu 9, Helsinki (1902), is a 5-storey (plus attic storey) Jugendstil or Art Nouveau work, in unpainted rough render decorated with patterns depicting seaweed made from granite insets.

[5] Nyström's most famous work was designed during the period of the partnership – though it is attributed to him alone – the Grand Hôtel Cascade (1903) (nowadays known as the Imatran Valtionhotelli) in Imatra.

Penttilä even campaigned for a Finnish National Romantic style of architecture on the pages of the journal he edited, Suomen Teollisuuslehti, with the designs showing exposed notched corner joints, rather than covering the logs with boarding, which had been the custom at that time.

Among their staff who went on to have distinguished careers were Emil Werner von Essen, Kauno Kallio, Kalle Kontio, Väinö Keinänen, Clas Axel Gylden and Uno Ullberg.

[2] While the main outer granite walls had mostly been preserved, Nyström devoted his creativity to a completely new interior using reinforced concrete to create new vaults, which while inspired by medieval church architecture have a more modern feel, a colourful example of Art Nouveau but also in a fluidity that has affinities with Expressionism which was already at its height at that time in central Europe.