From the geographical point of view Bielsko has been always situated very advantageously. Also its location on the important trade route from Cracow to Cieszyn and through Moravian Basin straight to Vienna and on routes leading to Oswiecim, Pszczyna, Wadowice, Zywiec and further on towards Slovakia brought the town many privileges, for instance free salt storage and running pubs.
The history of the town reaches the Middle Ages and the period of regional partition of the country.
Although the foundation act did not remain, the first historical note dates from 1312 when Bielsko is mentioned as a part of Cieszyn Duchy.
The Biala River flowing across the Bielsko-Biala centre (Bielsko and Biala were joined together in 1951 to form a new town) had been since the beginning of the l4th c. the frontier between the Cieszyn and the Oswiecim Duchies.
Besides the native Polish inhabitants the town had been created by the German colonists who settled a German "language island" among the Poles. The things came to such a point that before the Second World War in 1939 Bielsko was called "little Vienna".

Since the 16th c. Bielsko has gained the privilege to organize weekly meat market. Earlier it had gained rights to store salt without any taxes. Bielsko became famous for its clothing goods produced in the town thanks to accessibility of sheep wool and the power from the mountain streams necessary to produce cloth. Biala had its speciality, too. It was oxen and linen trade and because of the near frontier - smuggling salt and tobacco on Czech and Austrian market.
Both towns became more important and it brought their inhabitants considerable profits and fame.

The 18th and the l9th centuries brought Bielsko a great economic growth caused by fast development of trade and textile and engineering industry. It increased the wealth of the inhabitants and extended the urban areas. The inhabitants started to show interest in cultural and educational problems, they took up political and social activities. The nationality differentiation (the Poles, the Germans, the Jews) created a real phenomenon in that region of former Poland. Napoleon Bonaparte's wars were profitable for Bielsko and Biala because they brought a lot of military orders for the cloth for soldier? uniforms. It caused workshops mechanisation, introducing new appliances and the beginning of competition. The first machine was used in 1806 and 20 years later a steam one started to work. At the end of the 19th c. both strongly industrialised towns possessed about 150 textile and machinery factories. Their owners employed in each factory a few hundred workers who worked to maintain their families.
Most properties of rich enterprises and merchants were in hands of German and Jewish families-the owners of factories and shops.
Population of both towns increased regularly. In 1851 there were 7309 inhabitants in Bielsko, in Biala - 5187. In 1938 the population of Bielsko increased to 31099 persons. 50,4% of them declared Polish language as a native one, 49,1% declared German language, 0,5% Czech or any other.
In Biala there were 30 335 inhabitants. 69% of them used Polish, 29% German, 2% Czech or any other language. Jewish people were included in German language group. In 1921 the Jews constituted 14% of Bielsko inhabitants and 7,7% of Biala inhabitants.

It was only in 1918 when Poland regained its independence, Polish in habitants of both towns gradually obtained the same rights as German citizens In those days Bielsko belonged to Silesian Province and Biala to Cracow one There was a real fight for introducing Polish language as a second one into local schools, offices, Town Hall, Court, police, using Polish names of the streets electing Polish councillors. The first Polish mayor of Bielsko was appointed barely in 1930.
Germans were not pleased about that although they had economic and political superiority. There was open hostility towards Polish citizens that was close to Adolf Hitler's ideas, particularly among young nationalists, members of Jungdeutsche Partei (Young Germans Party) and members of fighting secret squads called freikorps. They had been waiting for their "great day" that came on the 2nd of September 1939 when the Polish army-attacked by them-had to leave the town. When the Nazi army entered Bielsko-Biala the dark. night of terror began.
Everyday denunciations became common as the local so-called volksdeutsches were well-informed who and what had done before the war. The Nazi concentration camp in Auschwitz (Oswiecim-Brzezinka) was so near. About 6000 Jews from Bielsko were killed in gas chambers. Tragic fate touched the Poles, too. At the beginning of the German occupation the local intelligentsia were shot, the other Poles were taken away to slave hard work inside Germany or to another concentration camps. Many members of national resistance were tortured and died in Gestapo prisons. Many outstanding persons (social and political leaders) lost their lives. The town was free only on the 10th-12th February 1945. Not only Nazi officers but also German informers ran away in fear of the Soviet Army. Many others had to leave the town during displacement. Finally both towns Bielsko and Biala became homogeneous in the field of nationality.

Before the Second World War Bielsko was said to be a town of the highest standard of living in Poland. Now the town was ready to join neighbouring Biala to create one urban body with common municipal structure, close links in culture and social institutions. During the German occupation the Nazi joined both towns in September 1939 and then incorporated them into so-called Reich.
But the real joining took place on the l-st of January 1951. From the modern history of the town May 1975 should be mentioned when a new Bielsko-Biala Province was established (as a result of new administrative partition of Poland) and January/February 1981 when Podbeskidzie Region was covered with the longest after August 1980 general strike which confirmed justness of workers protest.

From 1999, because of the new administration partition region of Bielsko-Biala former Province in included into Silesian Province.