Cárdenas (San Juan de Dios de Cárdenas) is a town in Matanzas Province, Cuba, about 150 km (75 mi) east of Havana.

Cárdenas is a maritime town on the level and somewhat marshy shore of a spacious bay of the northern coast of the island, sheltered by a long promontory. The city lies between the sea and hills. There are broad streets, various squares (including the Plaza de Colón, with a bronze statue of Columbus given to the city by Queen Isabella II. and erected in 1862) and substantial business buildings.

Cárdenas was founded in 1828, and in 1861 already had 12,910 inhabitants. In 1850 General Narciso Lopez landed here on a filibustering expedition, and held the town for a few hours, abandoning it when he saw that the people would not rise to support him in his efforts to secure Cuban independence. On the 11th of May 1898 an American torpedo-boat and revenue cutter here attacked three Spanish gun-boats, and Ensign Worth Bagley (1874–1898) was killed—the first American naval officer to lose his life in the Spanish-American War.

In the early 20th Century, Cárdenas was one of the principal sugar-exporting towns of Cuba. By 1907 the population was 24,280. The shallowness of the harbour necessitated lighterage and repeated loading of cargoes. The surrounding region is famed for its fertility. A large quantity of asphalt has been taken from the bed of the harbour. A flow of fresh water from the bed of the harbour is another peculiar feature; it comes presumably from the outlets of subterranean rivers. At El Varadero, on a peninsula at the mouth of the bay, there is fine sea-bathing on a long beach, and El Varadero is a winter resort.

The town's greatest claim to fame is being the home of attempted refugee Elián González. As of 2003, González attended Marcelo Salado Elementary School, whose director (principal) is Maribel Reyes.