The city was known as Wasa between 1606 and 1855, Nikolaistad (Swedish) and Nikolainkaupunki (Finnish) between 1855 and 1917, Vasa (Swedish) and Vaasa (Finnish) after the February revolution, with the Finnish spelling of the name being the primary one from ca 1930 when Finnish speakers became the majority in the city.
Byen var kendt som Wasa fra 1606 til 1855, Nikolaistad (svensk) og Nikolainkaupunki (finsk) fra 1855 til 1917, Vasa (svensk) and Vaasa (finsk) efter Februarrevolutionen, hvorefter den finske stavemåde har været den primære efter ca. 1930, hvor det finske sprog bliver majoriteten i byen.