Club Atlético River Plate is an Argentine professional sports club based in the Belgrano neighborhood of Buenos Aires. Founded in 1901, the club is named after the English name for the city's estuary, Río de la Plata. River's home stadium, Monumental, is the largest in South America. River had the highest average home attendance of any association football club in the world in 2023 with 84,567. With more than 350,000 members at the end of 2023, River is one of the largest sports clubs by membership. River Plate is also considered one of the Big Five of Argentine football, along with Independiente, San Lorenzo, Boca Juniors, and Racing Club.

Although a multi-sport club, River Plate is best known for its professional association football department, which has won Argentina's Primera División championship a record 38 times, most recently in 2023. River Plate have also won 16 national cups, making River Argentina's most successful team in domestic competitions with 54 titles. At international level, River have won 18 titles, including four Copa Libertadores, one Intercontinental Cup, one Supercopa Sudamericana, one Copa Sudamericana, three Recopa Sudamericanas, one Copa Interamericana, one Suruga Bank Championship, a record five Copa Aldaos, and one Tie Cup. In addition, River Plate's reserve team won the U-20 Copa Libertadores in 2012. After winning the 2014 Copa Sudamericana, 2015 Recopa Sudamericana and the 2015 Copa Libertadores, River Plate became the first team to simultaneously hold CONMEBOL's three current major international competitions.

River Plate are ranked first in the all-time Argentine Primera División table, having gained the most points, having played the most matches, and having the highest win percentage. River are also ranked first in the historical table of the Copa Libertadores, being the South American team with most games won and the most points gained. The club were placed ninth in the FIFA Club of the Century poll in 2000. In a survey published by the Argentine Football Association in 2016, 6 out of 11 players of the all-time greatest Argentina national team had played for River Plate.

River have a fierce rivalry with Boca Juniors. Matches between them are known as Superclásico, and the rivalry is among the most heated in the sport, due to the fixture's global popularity and both clubs having the most fans in Argentina. Notable players who have played for River include José Manuel Moreno, Adolfo Pedernera, Ángel Labruna, Amadeo Carrizo, Alfredo Di Stéfano, Omar Sívori, Daniel Passarella, Enzo Francescoli, Hernán Crespo, Javier Mascherano and Gonzalo Higuaín.