Club Atlético Boca Juniors (Spanish pronunciation: [kluβ aˈtletiko ˈβoka ˈʝunjoɾs]) is an Argentine professional sports club based in La Boca, a neighbourhood of Buenos Aires. The club is best known for its men's professional football team which, since its promotion in 1913, has always played in the Argentine Primera División. The team has won 74 official titles, the most by any Argentine club. National titles won by Boca Juniors include 35 Primera División championships, and 17 domestic cups. Boca Juniors also owns an honorary title awarded by the Argentine Football Association for their successful tour of Europe in 1925.

Internationally, Boca Juniors has won 22 major titles, with 18 organised by CONMEBOL and the rest organised jointly by the Argentine and Uruguayan Associations. Consequently, Boca is ranked third in the world in terms of number of complete international titles, after Real Madrid (34) and Egyptian side Al Ahly (26). Boca Juniors' international achievements also include one Tie Cup, one Copa de Honor Cousenier, and two Copa Escobar-Gerona, organized jointly by AFA and AUF together. Their success usually has the Boca Juniors ranked among the IFFHS's Club World Ranking Top 25, which they have reached the top position six times (mostly during the coaching tenure of Carlos Bianchi). Boca was named by the IFFHS as the top South American club of the first decade of the 21st century (2001–2010). It was designated by FIFA as the joint twelfth-best Club of the Century, in December 2000, occupying the same place as Liverpool of England, Internazionale of Italy, and Benfica of Portugal, among others.

Boca Juniors has a fierce rivalry with River Plate, and matches between them are known as the Superclásico. It is the most heated rivalry in Argentina and one of the biggest in the world, as the clubs are the two most popular in the country. Boca's home stadium is the Estadio Alberto J. Armando, better known colloquially as La Bombonera. The youth academy has produced many Argentine internationals who have played or are playing for top European clubs, such as Oscar Ruggeri, Sebastián Battaglia, Nicolás Burdisso, Carlos Tevez, Éver Banega, Fernando Gago, Leandro Paredes, and Nahuel Molina.

In addition to men's football, Boca Juniors has professional women's football and basketball teams. Other (amateur) activities held in the club are: bocce, boxing, chess, field hockey, futsal, artistic and rhythmic gymnastics, handball, martial arts (judo, karate, and taekwondo), swimming, volleyball, weightlifting, and wrestling. As of January 2023, Boca Juniors ranked first among the clubs with the most members in Argentina, with 315,879.