Increasing concerns over climate change in recent years have urged grassroots, professional sports organisations, and event organisers to consider resource demands, and the pressure they exert on the environment, and increase their economic and practical efficiency to remain viable. While sport is being acknowledged for its positive role in achieving wider externalities including environmental action, at the same time, sport organisations continue exerting pressure on the environment, with high greenhouse gas emissions through extensive travel and waste of resources. This inherent contradiction between the perceived role and practice of sport may impact its integrity and how it is seen by its multiple stakeholders such as volunteers, fans, participants, and spectators. Drawing on the concept of integrity, this chapter explores the insights of 10 European environmental sport volunteers who were members of PlayGreen, an Erasmus+ Sport funded project, on their motivations and commitment towards environmental conservation in and through sport, their perceptions on sport’s integrity and whether this aligns with their value orientations. The congruence between volunteers’ personal integrity to participate in environmental action and sport organisation’s integrity in facilitating and committing to climate action and sustainability is then discussed. Important implications for sport organisations towards upholding their integrity related to environmental responsibility are then considered.