Puerto Madryn (in Welsh, Porth Madryn) is a city in the province of Chubut in the Argentine Patagonia. It is the head town of the Biedma Department, and has about 58,000 inhabitants.

The town was founded on 28 July 1865, when 150 Welsh immigrants who came in the ship The Mimosa named the natural port Puerto Madryn in honour of Sir Love Jones-Parry, whose estate in Wales was named "Madryn". The settlement grew as a result of the building of the Central of Chubut Railway by Welsh, Spanish and Italian immigrants. This line, opened in 1888, linked it to Trelew via the lower Chubut River valley. Puerto Madryn is protected by the Golfo Nuevo, which is formed by Península Valdés and Punta Ninfas. It is an important centre for tourists visiting the natural attractions of the Península Valdés and the coast.

A new mall in the city center has helped tourism significantly, making Puerto Madryn a more attractive place for both international and domestic tourists visiting Patagonia. It is twinned with Nefyn, a small town on the Llyn Peninsula in North Wales, result of its great link with Welsh culture since the Welsh settlement in Argentina. The first of a two-Test tour to Argentina by the Wales national rugby union team was played in 2006 in Puerto Madryn, a 27–25 win for Argentina. Puerto Madryn is home to two football clubs; Club Social y Atlético Guillermo Brown, who play in Torneo Argentino A and Deportivo Madryn that currently play in Torneo Argentino B. A basketball team, Deportivo Puerto Madryn plays in the Liga Nacional de Básquetbol (LNB). Their home arena is known as the Deportivo Puerto Madryn Arena.