Luhansk Oblast (Ukrainian: Луганська область, romanized: Luhanska oblast; Russian: Луганская область, romanized: Luganskaya oblast), also referred to as Luhanshchyna (Луганщина), is the easternmost oblast (province) of Ukraine. Its administrative center is the city of Luhansk. The oblast was established in 1938 and bore the name Voroshilovgrad Oblast until 1958 and again from 1970 to 1991. Before the 2022 Russian invasion of Ukraine, its population was estimated at 2,102,921.

Important cities in Luhansk Oblast include Alchevsk, Antratsyt, Brianka, Kadiivka, Kirovsk, Krasnodon, Khrustalnyi, Luhansk, Lysychansk, Pervomaisk, Rovenky, Rubizhne, Sievierodonetsk and Sverdlovsk. All of the oblast is in the Donbas region.

In 2014, large parts of the oblast, including the capital Luhansk, came under the control of Russian-backed separatists who declared the Luhansk People's Republic, leading to a war against Ukrainian government forces. Since the 2022 Russian invasion of Ukraine, the oblast has come almost entirely under Russian occupation and has been the scene of heavy fighting, which continues in some places. In late September 2022, Russia declared the annexation of the entire oblast, along with three others, though the annexation remains internationally unrecognized. By July 2025, Russian forces had captured the last Ukrainian-held areas in Luhansk Oblast, bringing the entire region under their control, according to Russian-backed officials.

Luhansk Oblast is in far eastern Ukraine. Its north–south length is 250 km, and east–west width 190 km. It covers an area of 26,700 km², 4.42% of the total area of Ukraine.

The oblast has the longest segment of Ukraine's international border with Russia among other regions (see State Border of Ukraine), consisting of 746 km (464 mi). The abutting Russian oblasts are Belgorod Oblast to the north, Voronezh Oblast to the northeast, Rostov Oblast to the east. Abutting Ukrainian oblasts are Kharkiv Oblast to the west, and Donetsk Oblast to the south.

The region is located in the valley of the Siversky Donets river, which flows west to east through the oblast and splits it approximately in half. The southern portion of the region is elevated by the Donetsk Ridge, which is close to the southern border. The highest point is Mohyla Mechetna (367 m (1,204 ft)), the highest point of Donetsk Ridge. The left bank of the Siversky Donets is part of the Starobilsk Plain. To the north this transforms into the Central Russian Upland.

The territory was formerly part of the Wild Fields, and former administrative units in the territory of the current oblast included Sloboda Ukraine, Slavo-Serbia, Yekaterinoslav Governorate, Donets Governorate and Donetsk Oblast.

The oblast originated in 1938 as Voroshylovhrad (Russian: Voroshilovgrad) Oblast (Ukrainian: Ворошиловградська область, romanized: Voroshylovhradska oblast) after the Donetsk Oblast was split between Voroshylovhrad and Stalino (today Donetsk Oblast) oblasts. Following the Soviet invasion of Poland, Starobilsk was the location of a prisoner of war camp for Poles, who were then massacred in the Katyn massacre in 1940. After the invasion by Nazi Germany in 1941, the region came under a German military administration, due to its proximity to frontlines. It was occupied at the end of 1942 as part of Case Blue German offensive directed towards Stalingrad.