Background: Opportunistic prostate-specific antigen (PSA) screening may reduce prostate cancer mortality risk but is associated with false positive results, biopsy complications and overdiagnosis. Although different organisations have emphasised the importance of shared decision making (SDM) to assist men in deciding whether to undergo prostate cancer screening, recent evaluations show that the available decision aids fail to facilitate SDM, mainly because they do not consider the patients’ perspective in their design. We aim to systematically develop and test a patient decision aid to promote SDM in prostate cancer screening, following the Knowledge to Action framework. Methods: (1) Feasibility study: a quantitative survey evaluating the population and clinician (urologists and general practitioners) knowledge of the benefits and risks derived from PSA determination and the awareness of the available recommendations. Focus groups to explore the challenges patients and clinicians face when discussing prostate cancer screening, the relevance of a decision aid and how best to integrate it into practice. (2) Patient decision aid development: Based on this data, an evidence-based multicomponent SDM patient decision aid will be developed. (3) User-testing: an assessment of the prototype of the initial patient decision aid through a user-testing design based on mix-methods (questionnaire and semi-structured review). The decision aid will be refined through several iterative cycles of feedback and redesign. (4) Validation: an evaluation of the patient decision aid through a cluster-randomised controlled trial. Discussion: The designed patient decision aid will provide balanced information on screening benefits and risks and should help patients to consider their personal preferences and to take a more active role in decision making. Conclusions: The well-designed patient decision aid (PDA) will provide balanced information on screening benefits and risks and help patients consider their personal preferences.