Athens has a long tradition in sports and sporting events, being home of the most important clubs in Greek sports and having a large number of sports facilities. The city has also served as a host of several sports events of international notability.

Athens has hosted the Summer Olympic Games twice, in 1896 and 2004. The 2004 Summer Olympics inspired the development of the Athens Olympic Stadium, which has since gained a reputation as one of the most beautiful stadia in the world, and one of its most interesting modern monuments. The biggest stadium in the country, it has hosted two finals of the UEFA Champions League, in 1994 and 2007. The other major stadium of Athens, located in Piraeus area, is the Karaiskakis Stadium, a state-of-the-art sports and entertainment complex, host of the 1971 UEFA Cup Winners' Cup Final. Athens has hosted the Euroleague final three times, the first in 1985 and second in 1993, both at the Peace and Friendship Stadium, most known as SEF, one of the largest and most attractive indoor arenas in Europe, and the third in 2007 at the Olympic Indoor Hall. A large number of events in other sports such as athletics, volleyball, water polo etc., has also been hosted in the capital's venues.

Athens is home to three prestigious European multi-sport clubs: Olympiacos, Panathinaikos, AEK Athens. In football, Olympiacos have dominated the domestic competitions, Panathinaikos made it to the 1971 European Cup Final, while AEK Athens is the other member of the big three. These clubs also hold prominent basketball departments; Panathinaikos and Olympiacos are among the top powers in European basketball, having won the Euroleague five times and once respectively, with AEK Athens being the first Greek team to win a European trophy in any team sports. Other clubs with great tradition in sports within Athens are Panionios, Panellinios, Ethnikos Piraeus and Maroussi. Athenian clubs have also had significant domestic and international success in other sports.

The Athens area encompasses a variety of terrain, notably hills and mountains rising around the city, and the capital is the only major city in Europe to be bisected by a mountain range. Four mountain ranges extend into city boundaries and thousands of miles of trails crisscross the city and neighbouring areas, providing exercise and wilderness access on foot and bike. Beyond Athens and across the county a great variety of outdoor activities are available and popular, including skiing, rock climbing, hang gliding and windsurfing. Numerous outdoor clubs serve these sports, including the Athens Chapter of the Sierra Club, which leads over 4,000 outings annually in the area.