This study explored environmental antecedents of online word-of-mouth (WOM) within the realm of information value and empirically assessed their influences on both low- and high-informativeness WOM behaviors (i.e., like and share behaviors, respectively) in a natural online setting (i.e., Facebook pages of professional sport teams). With survey data and online secondary data, content analysis and negative binomial regression were conducted. The results revealed the significant impacts of environmental antecedents associated with content provision and game attractiveness on fans’ like and share behaviors. The findings confirmed the importance of information value in determining online WOM behavior and shed new light on the investigation of this consumer behavior in sport marketing communications. Actionable suggestions are implicated in terms of utilizing the identified environmental variables to maximize the marketing benefits of fans’ online WOM behavior.