Uno Werner Ullberg was born on 15 February 1879 in Vyborg, Southern Karelia (now Russia). Ullberg received his diploma of architecture from the Polytechnical Institute of Helsinki in 1903. Before finishing his studies, Ullberg did an expedition to Karelia together with fellow architecture students, J. Kekkonen and A. Tawastjerna. In 1904 Ullberg made a study trip to England, Scotland and France and in 1909-1910 to Italy, Austria, Germany, Denmark and Sweden.
Before establishing his own office in Vyborg 1909, Ullberg first worked as a draughtsman at Nyström-Petrelius-Penttilä Architects and later had a shared office with architect C.A. Gyldén. His main work is the Viipuri Art Museum and Art School, completed in 1930. The years 1932–1936 Ullberg was the city architect of Viborg, and after that he worked at the National Board of Health, designing hospital buildings.
Uno Ullberg died on 12 January 1944 in Helsinki. He is buried in the Hietaniemi Cemetery in Helsinki. Alvar Aalto designed Ullberg’s gravestone.