In professional boxing, the undisputed champion of a weight class is the boxer who simultaneously holds world titles from all sanctioning organizations recognized as major by each other and the boxing community). The term "undisputed" means that there is no dispute that the boxer is the champion because there are no other champions to challenge this fact. Prior to the 1960s, most champions were "undisputed," although the term was rarely used). Early boxing champions at various weight divisions were established by acclamation between 1880 and 1920. Once a consensus champion had been awarded the title, the championship could usually be taken only by beating the reigning holder, establishing a lineal championship).

In the four-belt era, which began in 2004, an undisputed champion is a fighter who holds all four major championship belts (IBF, WBA, WBC, and WBO) in a division. A unified champion, on the other hand, is one who holds two or more of the major sanctioning titles in a division.

It is worth noting that there are often more champions per division than contenders, with four widely recognized and often self-serving sanctioning organizations, each with its own rankings, constituents, and agendas. Therefore, the emergence of one legitimate, fully deserving, and universally acknowledged champion for a weight class is what boxing fans hope for and strive for.