The first settlers to reach the territory, presently nominated Rio Azul, were originally from Portugal; Claudio Amancio de Oliveira, Domingos Soares Ramos, Frederico Ferreira, Joaquim Correia Lopes, Joaquim Marinho and Jose Lourenço Cardoso arrived here around 1885 bringing along their tradition and customs to the region.

Opening the pathway in the new land was a hard work carried out by the pioneers who settled in the region launching roots to a village initially named Roxo Roiz.

With the extension of the tracks of the Railroad São Paulo-Rio Grande do Sul, to the town in December 1902 was inaugurated the railway station which received the same name of the town of Roxo Roiz.

The arrival of the railroad boosted progress to the region. The advent of trains opened the pathway to the economic development of agriculture, extractive industries of wood and yerba mate, as well as, agricultural activities and livestock with extraordinary growth. This successful cycle caused a massive movement of new inhabitants to the forthcoming town.

The Decree No. 461 estabilished a police district named “Cachoeira”, settled in Roxo Roiz Train Station, in the city of Irati , in November 27th, 1907.

Around 1908, the village received immigrants from Poland and Ukraine nation. These settlers founded a district called Colônia Rio Azul.

In 1913, Roxo Roiz was elevated to the status of Judicial District, to Later, in 1918 became the an independent county.

In the meantime the city’s name was changed to Marumby and, in 1929, the municipality was finally given its current name, Rio Azul.