Western Ukraine or West Ukraine (Ukrainian: Західна Україна, romanized: Zakhidna Ukraina, IPA: [ˈzɑxidnɐ ʊkrɐˈjinɐ]) refers to the western territories of Ukraine. There is no universally accepted definition of the territory's boundaries, but the contemporary Ukrainian administrative regions (oblasts) of Chernivtsi, Ivano-Frankivsk, Lviv, Ternopil and Zakarpattia (which were part of the former Austro-Hungarian Empire) are typically included. In addition, Volyn and Rivne oblasts (parts of the territory annexed from the Polish–Lithuanian Commonwealth during its Third Partition) are also usually included. In modern sources, Khmelnytskyi Oblast is often included because of its geographical, linguistic and cultural association with Western Ukraine, although this cannot be confirmed from a historical and political point of view. It includes several historical regions such as Carpathian Ruthenia, Halychyna including Pokuttia (the eastern portion of Eastern Galicia), most of Volhynia, northern Bukovina and the Hertsa region, and Podolia. Western Ukraine is sometimes considered to include areas of eastern Volhynia, Podolia, and the small northern portion of Bessarabia.

The area of Western Ukraine was ruled by various polities, including the Kingdom of Galicia–Volhynia, which became part of the Polish–Lithuanian Commonwealth, but also the Principality of Moldavia; it would then variously come under rule of the Austrian Empire, Austria-Hungary, the Second Polish Republic, the Kingdom of Romania, and finally the Soviet Union (via the Ukrainian Soviet Socialist Republic) in 1939 and 1940 following the invasion of Poland and the Soviet occupation of Bessarabia and Northern Bukovina, with the borders finalized after the end of World War II. After the dissolution of the Soviet Union, it became part of the independent Ukrainian state.

Western Ukraine is known for its exceptional natural and cultural heritage, several sites of which are on the List of World Heritage. Architecturally, it includes the fortress of Kamianets, the Old Town of Lviv, the former Residence of Bukovinian and Dalmatian Metropolitans, the Tserkvas, the Khotyn Fortress and the Pochayiv Lavra. Its landscapes and natural sites also represent a major tourist asset for the region, combining the mountain landscapes of the Ukrainian Carpathians and those of the Podolian Upland. These include Mount Hoverla, the highest point in Ukraine, Optymistychna Cave, the largest in Europe, Bukovel Ski Resort, Synevyr National Park, Carpathian National Park or the Uzh National Nature Park protecting part of the primary forests included in the Carpathian Biosphere Reserve.

The city of Lviv is the main cultural center of the region and was the historical capital of the Kingdom of Galicia–Volhynia. Other important cities are Chernivtsi, Rivne, Ivano-Frankivsk, Ternopil, Lutsk, Khmelnytskyi and Uzhhorod.

Western Ukraine, takes its roots from the Kingdom of Galicia–Volhynia, a successor of Kievan Rus' formed in 1199 after the weakening of Kievan Rus' and attacks from the Golden Horde.

Following the 14th century Galicia–Volhynia Wars, most of the region was transferred to the Crown of Poland under Casimir the Great, who received the lands legally by a downward agreement in 1340 after his nephew's death, Bolesław-Jerzy II. The eastern Volhynia and most of Podolia was added to the territory of the Grand Duchy of Lithuania by Lubart.

The territory of Bukovina was part of Moldavia since its formation by voivode Dragoș, who was departed by the Kingdom of Hungary, during the 14th century.

After the 18th century partitions of Poland (Polish–Lithuanian Commonwealth), the territory was split between the Habsburg monarchy and the Russian Empire. The modern south-western part of Western Ukraine became the Kingdom of Galicia and Lodomeria, after 1804 crownland of the Austrian Empire. Its northern flank with the cities of Lutsk and Rivne was acquired in 1795 by Imperial Russia following the third and final partition of Poland. Throughout its existence Russian Poland was marred with violence and intimidation, beginning with the 1794 massacres, imperial land-theft and the deportations of the November and January Uprisings. By contrast, the Austrian Partition with its Sejm of the Land in the cities of Lviv and Stanyslaviv (Ivano-Frankivsk) was freer politically perhaps because it had a lot less to offer economically. Imperial Austria did not persecute Ukrainian organizations. In 1846, the Austrian government used the peasant uprising to decimate Polish nobles, who were organising an uprising against Austria. In later years, Austria-Hungary de facto encouraged the existence of Ukrainian political organizations in order to counterbalance the influence of Polish culture in Galicia. The southern half of West Ukraine remained under Austrian administration until the collapse of the House of Habsburg at the end of World War One in 1918.