Electronic sports (esports), as a professionalized form of organized video game competition, enjoys incredibly high popularity worldwide. Its current limitation necessitates the emergence of amateur esports, a specific form of esports designated for mass gamer participation. As amateur esports is in the initial developmental stage, mass gamers’ transformation into amateur participants is the current focus. However, we know little about this transformation due to scant research. Thus, this study attempts to understand the transformation of mass gamers into amateur esports participants by investigating the relationship between mass gamers’ everyday gaming behaviors and their amateur esports participation. Specifically, relying on use and gratification theory, this study learns what everyday gaming behaviors impact amateur esports participation intention. Furthermore, this study also explains the mechanism of these influences through the lens of commitment. This study contributes to research and practice regarding amateur esports development.