IntroductionCompetitive sport is increasingly affected by environmental challenges. Athletes compete in performance-oriented systems that often constrain pro-environmental action. Navigating ecological sustainability-related cognition and affect may therefore impose additional mental load on athletes and require self-regulation, potentially competing with performance-relevant cognitive and emotional resources, consistent with resource-based models of self-control. However, little is known about how athletes experience ecological sustainability within their competitive sport and how they perceive its impact on performance. This qualitative study examined how competitive athletes cognitively and affectively engage with ecological sustainability and how these experiences are perceived in relation to their sporting performance.MethodsSemi-structured interviews were conducted with nine athletes from different sports and competitive levels. Data were analyzed using structured deductive qualitative content analysis.ResultsAthletes expressed strong pro-environmental attitudes but experienced a pronounced and recurring value-action gap driven by structural constraints such as competition schedules, travel demands, and sponsorship obligations. Ecological sustainability-related cognition and affect (e.g., guilt, frustration, sadness) were salient across sports but were actively regulated, suppressed, or compartmentalized in performance contexts to maintain focus and competitive readiness. While athletes rarely reported immediate performance impairments, sustainability-related concerns contributed to indirect performance-relevant strain through travel fatigue, disrupted preparation, and cumulative mental load affecting recovery and well-being. Engagement in sustainability initiatives emerged as a central coping strategy and was often experienced as empowering; sport itself served as an important coping context.DiscussionOverall, ecological sustainability functioned both as a psychological burden and a motivational resource in competitive sport. While athletes expressed strong motivation to engage with sustainability, their ability to act consistently with these values was often constrained by both the structures of competitive sport and individual decisions.