PurposeThe purpose of this research is to examine fans' perceptions of pro-environmental sustainability initiatives promoted by a professional sport club and the ensuing effects on a triple bottom line (TBL) approach (i.e. fans' socially, environmentally and economically favourable behaviours).Design/methodology/approachData were collected in two different steps using an online self-administered questionnaire (n1 = 1,043; n2 = 2,167) distributed to fees-paying members registered in the club's database. The analysis was carried out though structural equation modelling.FindingsThe results indicate good psychometric properties of the scale used to measure fans' perceptions of a club's pro-environmental sustainability initiatives (perceptions of pro-environmental sustainability initiatives in sports; p-PESIS). Additionally, there is a positive effect of p-PESIS on fans' social behaviours as well as on their daily environmental actions. Furthermore, p-PESIS also shows a positive effect at improving fans' economic activities towards the club.Originality/valueExtending previous research, the authors tested a scale to measure fans' responses to pro-environmental sustainability initiatives in sport and examined their links to the TBL dimensions. Pro-environmental sustainability initiatives in sport benefit not only the club itself (by reinforcing fans' activities with the club) but also society as a whole, as it can promote fans' conscientiousness and likelihood to behave in environmentally and socially favourable ways.