The town's territory was firstly settled already since the last Ice Period what was about 20 000 years B.C. From that period originates the known settlement in the quarter of Žilina called Závodie. The town was inhabited also in Bronze Age, in Iron Age and in Roman era.
Our predecessors settled in the today’s town's territory in the 5th century. The evidence of the Slavonic settlement could be found in the premises of the following historical castles: Hricov, Sulov, Lietava and Strecno. Slavonic barrows were found in Žilina - Chrastie, Žilina - Banova , Bitarova and Krasnany. From the 9th century is settlement located at Bôrik (where is today’s park), and burial places at nearby village called Bánová. First written document about the town's territory was dated in 1208 and was mentioned under the name Terra de Selinan .Terra de Selinan was a document signed by Bishop Thomas from Nitra. Here was mentioned the word Selinan, which was derived from the Slovak word Žilinany. In 1297 the name Žilina appears in some writings. According to the written documents dated 12 July 1321 Žilina was already a town. The King Charles I Robert of Anjou during his royal visit to our town on 12 July 1321 granted privileges of a free town to Žilina which then were confirmed also by Sigismund I of Luxembourg (1397) and by Vladislaw II Jagello (1497).

Very important legal and language document of European importance is the Book of Žilina the origin of which reaches back to the year 1378 when Mikuláš of Luková made for our town a German copy of the Law of Magdeburg town respected by the town Csesin. Another part of Town Book is translation of this law into slovakized Czech language (1473) and the last (third) part is a writing about properties transfers and privat law registration since 1380 up to 1561(last written entries in the book). The Book is treasured at the State District Archives in Žilina.
In 1381 the Slovaks living in the town were positively responded by the ruler when they asked for equal rights with the German colonists. The bill Privilegium pro Slavis (privileges for the Slovaks) was issued on 7 May 1381 by the Hungarian and Polish King Lodovic I, the Great during his visit to Žilina. This important event is commemorated by a memorial tablet on the wall of the Town Hall of Žilina. In the year 1431 hussite army gained and burned out Žilina. The town fell down economically after being left by the Hussites troops.