The Commissioner of Baseball is the chief executive officer of Major League Baseball (MLB) and the associated Minor League Baseball (MiLB) – a constellation of leagues and clubs known as "organized baseball". Under the direction of the Commissioner, the Office of the Commissioner of Baseball hires and maintains the sport's umpiring crews, and negotiates marketing, labor, and television contracts. The commissioner is chosen by a vote of the owners of the teams. The incumbent MLB commissioner is Rob Manfred, who assumed office on January 25, 2015.

Major League Baseball (MLB) is a professional baseball league and the highest level of organized baseball in the United States and Canada. One of the big four major leagues, MLB comprises 30 teams, divided equally between the National League (NL) and the American League (AL), with 29 in the United States and 1 in Canada. Formed in 1876 and 1901, respectively, the NL and AL cemented their cooperation with the National Agreement in 1903, making MLB the oldest major professional sports league in the world. They remained legally separate entities until 2000, when they merged into a single organization led by the Commissioner of Baseball. MLB is headquartered in Midtown Manhattan.