Top athletes face various challenges in their career on and off the sports field. Sport psychologists teach techniques to help athletes to cope with these challenges. Over the last 30 years, the techniques used stem mainly from psychological skills training (PST), which is influenced mainly from cognitive-behavioral theories. Recently, interest in mindfulness-based interventions has increased in sport psychology. This article identifies the limits of PST and presents theoretical considerations how mindfulness-based interventions can amend PST. Further, it addresses in what form and by what mechanisms athletes could benefit. In reviewing current mindfulness literature, we conclude that it is important to distinguish between mindfulness practice and dispositional mindfulness. Mindfulness practice means the methods through which mindfulness is fostered, whereas dispositional mindfulness describes the tendency to be mindful in everyday life. In our conceptualization, we differ between three interwoven facets of mindfulness practice (intention, attention, and attitude), which are associated with six components of dispositional mindfulness. We consider that athletes with a higher degree in mindfulness practice and dispositional mindfulness will enhance the level of several required psychological skills through various impact mechanisms. Based on theoretical considerations, we suggest bare attention, experiential acceptance, values clarifications, self-regulation/negative emotion regulation, clarity about one’s internal life, exposure, flexibility, non-attachment, and rumination as possible impact mechanisms. A greater knowledge of the conceptualization of mindfulness and its impact on psychological skills could develop and improve the effectiveness of mindfulness based interventions in sports.