Czech Silesia is the name given to the part of the historical region of Silesia located in the present-day Czech Republic. While not today an administrative entity in itself, Czech Silesia is, together with Bohemia and Moravia, one of the three historical Czech lands. In this context, it is often mentioned simply as "Silesia", even though it is only around one tenth of the area of the historic land of Silesia.

Silesia lies within the north-east of the Czech Republic, predominantly in the Moravian-Silesian Region, with a section in the northern Olomouc Region. It is almost identical in extent with the Duchy of Upper and Lower Silesia, also known as Austrian Silesia before 1918; between 1938 and 1945, part of the area was also alluded to as Sudeten Silesia (German: Sudetenschlesien, Lower Silesian: Sudetaschläsing, Czech: Sudetské Slezsko, Silesian: Sudecki Slunsk, Polish: Slask Sudecki): a reference to the Sudetenland.

Modern-day Czech Silesia derives primarily from a small part of Silesia that remained within the Bohemian Crown and the Habsburg Monarchy at the end of the First Silesian War in 1742, when the rest of Silesia was ceded to Prussia. It was re-organised as the Duchy of Upper and Lower Silesia, with its capital at Opava (German: Troppau, Polish: Opawa). In 1900, the Duchy occupied an area of 5,140 km² and had a population of 670,000.

In 1918, the former Duchy formed part of the newly created state of Czechoslovakia, except the Cieszyn Silesia, which was split between Czechoslovakia and Poland in 1920, Czechoslovakia gaining its western portion. Hlucín Region (Czech: Hlucinsko, German: Hultschiner Landchen), formerly part of Prussian Silesia, also became part of Czechoslovakia under the Treaty of Versailles in 1920.

Following the Munich Agreement of 1938, most of Czech Silesia became part of the Reichsgau Sudetenland and Poland occupied the Zaolzie area on the west bank of the Olza (the Polish gains being lost when Germany occupied Poland the following year).

With the exception of the areas around Cieszyn, Ostrava, and Hlucín, Czech Silesia was predominantly settled by German-speaking populations up until 1945. Following the Second World War, Czech Silesia and Hlucínsko were returned to Czechoslovakia and the ethnic Germans were expelled. The border with Poland was once again set along the Olza (although not confirmed by treaty until 1958).