Characteristics of the included studies.

BackgroundBlood donation is vital for health systems, yet global shortages persist due to low donor participation. Understanding the psychological determinants of donation is critical to improving recruitment and retention. The Theory of Planned Behavior has been widely applied to predict donation intention and behavior.ObjectiveThis review aimed to map and synthesize the evidence on blood donation practices and behavioral intentions through the lens of the Theory of Planned Behavior, identifying key determinants, barriers, facilitators, and research gaps.MethodsWe conducted a scoping review guided by PRISMA-ScR. Major databases (PubMed, Web of Science, CINAHL, Cochrane, Hinari, and the WHO library) and grey literature were searched for studies published between January 1, 2004, and August 31, 2025. Eligible studies applied the theory of planned behavior constructs to blood donation practices across different populations and settings.ResultsNineteen studies met the inclusion criteria. Most (n = 12) focused on students, while others examined healthcare workers or established donors. Cross-sectional designs predominated. Theory of planned behavior constructs, including attitude, perceived behavioral control, self-efficacy, moral norms, and anticipated regret were strong predictors of intention to donate blood. However, intention alone was insufficient to consistently predict actual donation behavior. Reported barriers included fear, low self-efficacy, and systemic challenges; facilitators included altruism, positive attitudes, social influence, and prior donation experience.ConclusionTheory of planned behavior provides a robust framework for understanding blood donation intentions, but augmenting it with moral norms and past behavior may improve the prediction of actual behavior. Interventions should target attitudes, perceived behavioral control, self-efficacy, and supportive social norms, while addressing systemic barriers, to strengthen voluntary donor recruitment and retention.