Kastrup Boldklub (Kastrup BK or KB for short) is a Danish football club based in the suburb of Kastrup (Tårnby Municipality) on Amager. As of the 2024–25, the club's first senior men's team play in Copenhagen Series (level 6). The club was founded on 4 May 1933 as Boldklubben Funkis and changed to the current name in 1941. The senior men's football team have since 1985 primarily played their home games at Kastrup Idrætsanlæg located at Røllikevej, Kastrup next to the club house, but have previously played their matches at Tårnby Stadium during their tenure in the higher ranking leagues, and occasionally still do. Earlier in their history, the club was located at John Tranums Alle.

Kastrup Boldklub has spent a total of nine seasons in the highest football league in Denmark, the last in 1987. Their best result was set in the 1979 season, when the first team finished in fourth place in the top league and thus qualified for the 1980 Intertoto Cup. The club has participated in two elite superstructures, Amager United (2002–2006) and FC Amager (2008–2009) and enjoy long-standing rivalries against neighbouring clubs BK Fremad Amager and AB Tårnby (previously Tårnby Boldklub). The Tårnby-based club has fielded eight active players on the national football teams, seven youth male players for the teams of Under-17, Under-19, Under-21, Denmark national amateur football team, Denmark national B-football team, and a senior player (Adam Fogt) on the Denmark national football team, including one female player on a youth team.

The person responsible for direction of the first senior team has traditionally been given the title of head coach/trainer.

^‡: Won by reserve team