Montluçon (French: [mɔ̃lysɔ̃] ^ⓘ; Occitan: Montleçon [munləˈsu]) is a commune in central France on the river Cher. It is the largest commune in the Allier department, although the department's prefecture is located in the smaller town of Moulins. Its inhabitants are known as Montluçonnais. The town is in the traditional province of Bourbonnais and was part of the mediaeval duchy of Bourbon.

Montluçon is located in the northwest of the Allier department near the frontier of the Centre-Val de Loire and Nouvelle-Aquitaine regions.

Montluçon is linked with surrounding regions and towns via four main road axes, plus the highway A71 from Orléans to Clermont-Ferrand; through a railway linking in the North Vierzon then Paris (3-5h). Formerly the canal de Berry linked Montluçon towards the north.

Montluçon is 106 kilometres (66 miles) south of Bourges, 340 km (211 miles) from Paris, 95 km (59 mi) from Clermont-Ferrand, 280 km (174 mi) (3h) from Lyon, 150 km (93 mi) (2h) from Limoges and 400 km (249 mi) from the Atlantic coast.

Montluçon is close to the Méridienne verte (an architectural project marking the Paris meridian) and to the Greenwich meridian.

Montluçon is also close to the geographic centre of Metropolitan France.

Montluçon was built in the Middle Ages. The first mention of a place called Monte Lucii (Mont de Lucius) dates from the eleventh century. Guillaume, son of Archambaud IV of Bourbon, built the castle in a defensible position on a small rocky hill on a bend in the river Cher.

The town, which formed part of the duchy of Bourbon, was taken by Henry II in 1171, and by Philip Augustus in 1181; the English were finally driven out in the 14th century.