Growing ethical concern about equestrian sport is reflected in publications by regulatory authorities, animal charities, and the lay press; and in government debate and social media. However, attempts by regulators and stakeholders to address ethical issues in equine sport have been discipline specific and ad hoc. Ethical frameworks can help stakeholders to make contextual decisions about what should or should not be done in a particular situation. However, when existing animal welfare frameworks and existing sports ethics frameworks are reviewed in this paper, it becomes clear that none provide us with a suitable or sufficient tool for considering ethical issues which can arise in situations where the athlete is a non-human, non-consenting participant. This paper presents the theoretical development of a novel ethical framework, with the aim of providing stakeholders with a tool which they might apply to the consideration of the ethical questions which inevitably arise in relation to (equestrian) sport. The derivation and limitations of the ethical framework are explained. The use of the framework will serve both to underwrite the continuation of the social license to use horses in sport and also to enable those within equestrian sport to critically assess existing and proposed practices and to make welfare-improving adjustments to practice if/where necessary. The theoretical framework as presented here is currently being practically tested and refined in consultation with industry stakeholders, and that research will be submitted for publication in due course.