The Magdalena River (Spanish: Río Magdalena, Spanish pronunciation: [ˈri.o maɣðaˈlena]; less commonly Rio Grande de la Magdalena)^[5] is the main river of Colombia, flowing northward about 1,528 kilometres (949 mi) through the western half of the country. It takes its name from the biblical figure Mary Magdalene. It is navigable through much of its lower reaches, in spite of the shifting sand bars at the mouth of its delta, as far as Honda, at the downstream base of its rapids. It flows through the Magdalena River Valley.

Its drainage basin covers a surface of 273,000 square kilometres (105,000 sq mi), which is 24% of the country's area and where 66% of its population lives.

The Magdalena River is the largest river system of the northern Andes, with a length of 1,612 km.^[6] Its headwaters are in the south of Colombia, where the Andean subranges Cordillera Central and Cordillera Oriental separate, in Huila Department. The river runs east then north in a great valley between the two cordilleras. It reaches the coastal plain at about nine degrees north, then runs west for about 100 km (62 mi), then north again, reaching the Caribbean Sea at the city of Barranquilla in the zone known as Bocas de Ceniza.

Due to its geographical position in the north of South America, the Magdalena River was since precolumbian times a route towards the interior of present-day Colombia and Ecuador. Several Carib-speaking peoples such as the Panche and the Yariguí ascended through the western bank of the river, while its eastern portion was inhabited by the Muisca civilization, which called the river Yuma.

Likewise, the Spanish conquistadores who arrived to today's Colombia early in the 16th century used the river to push to the wild and mountainous inland after Rodrigo de Bastidas discovered and named the river on April 1, 1501. During the Spanish colonization of the Americas, the river was the only transport link communicating Bogotá with the Caribbean Sea port Cartagena de Indias and thus with Europe.

The Magdalena Campaign of Pierre Labatut and Simón Bolívar took place along the Magdalena River.

In 1825, the Congress of Colombia awarded a concession to establish steam navigation in the Magdalena River to Juan Bernardo Elbers,^[21] but his company closed shortly after. By 1845, steamboats regularly travelled on the river^[22] until 1961, when the last steamers ceased operation.^[21]

Much of the film Love in the Time of Cholera takes place in the historic, walled city of Cartagena in Colombia. Some screenshots showed the Magdalena River and the Sierra Nevada de Santa Marta mountain range.

The General in His Labyrinth, by Gabriel García Márquez, is a fictionalized account of the final voyage of Simón Bolívar down the Magdalena River, where he revisits many cities and villages along the river.

In Magdalena: River of Dreams (Knopf, 2020), Canadian writer, anthropologist, and explorer Wade Davis travels the length of the river by boat, on foot, by car, and on horseback combining descriptions of nature with episodes from Colombian history.^[23]