To reduce global warming and climate change, the German government plans to implement a carbon tax, which will also affect sport organizations. This study investigates how much sport club members are willing to pay for environmental measures and how sport-specific, club-specific, environmental, and socio-demographic factors are associated with their willingness-to-pay. In 2019 and 2020, active adult sport club members in five team/racket sports were sampled using an online survey in Germany (n = 3036). The contingent valuation method was applied to estimate sport club members’ willingness-to-pay for environmental measures. Regression analyses were employed to investigate a set of factors that are associated with club members’ decision to pay at all and the amount of willingness-to-pay. The results show that 64.3% of respondents reported a positive willingness-to-pay. The average willingness-to-pay for environmental measures amounts to EUR 14.53 per year and to EUR 22.59 for those reporting a positive willingness-to-pay. The results of t-tests show that club members stating a positive WTP differ significantly from members who are not willing to pay anything in terms of sport-specific, club-specific, environmental, and socio-demographic factors. The logistic regression results indicate that the likelihood of reporting a positive willingness-to-pay increases with increasing environmental consciousness, educational level, weekly practice hours, identification and satisfaction with the club, and subjective well-being, while age has a U-shaped effect. The results of a Tobit model show that the amount of willingness-to-pay is positively determined by environmental consciousness, educational level, and satisfaction with the club. The findings suggest that the majority of club members are willing to pay higher membership fees for the implementation of environmental measures in sport clubs. Increasing members’ level of environmental consciousness through educational initiatives represents a way for sport policy and sport managers to help increase financial support for environmental measures among club members.