The following is a list of squads for each nation competing at the 2013 World Baseball Classic (WBC). The deadline for submitting provisional rosters was January 16, but teams had until February 20 to finalize their roster decisions.^[1] Provisional rosters were announced on January 17,^[2] and final rosters were announced on February 20.^[3]

In the WBC, starting pitchers are allowed to throw 65 pitches in first-round games. This limit increases to 80 in the second round and 95 in the semifinal and final rounds. If a starting pitcher throws over 50 pitches in a game, he must not pitch again for a minimum of four days. Relief pitchers are allowed to pitch on consecutive days only if they threw less than 30 pitches on the previous day. Pitchers are not allowed to pitch on three consecutive days under any circumstances.^[1]

Injured players could be freely replaced before the team's first game. Once a team begins play, injured catchers can be replaced at any time, but other injured players cannot be replaced until the team advances to the next round of the tournament.^[3]

The United States provisional roster is made up entirely of players from Major League Baseball (MLB), and the Dominican Republic provisional roster has only one player not signed to a team for the 2013 season. The Canadian team has 12 players who appeared in MLB in 2012, while Japan has none (three prominent Japanese MLB players, Yu Darvish, Ichiro Suzuki and two-time defending WBC MVP Daisuke Matsuzaka, chose not to play).^[2] Though five members who competed for the Cuban national team in the 2009 WBC have since defected, the Cuban team is considered strong.^[4] Three members of MLB.com's Top 100 prospect list are participating in the 2013 WBC: Xander Bogaerts, Eddie Rosario, and Jameson Taillon.^[5]