Within psychological research, the concept of forgiveness has gained recognition for its potential impact on health, underlining the need for culturally adapted assessment tools and longitudinal studies to substantiate its effects. In this two‐phase research project, we initially adapted the Rye Forgiveness Scale (RFS) to measure state forgiveness in the Polish context with 740 participants. Reliability analysis and confirmatory factor analysis confirmed the RFS's structure and internal consistency (absence of negative α = 0.87, presence of positive α = 0.86, full scale α = 0.84). Positive associations with other measures of forgiveness, religiosity, connection to nature, and mental well‐being validated the scale's efficacy. The second phase evaluated the impact of state forgiveness on the mental health of 214 HIV‐positive Polish individuals across three 6‐month intervals. Utilizing the stress‐and‐coping model, this phase investigated forgiveness as a protective factor against negative mental health outcomes. The findings indicated that forgiveness could positively influence mental health, underscoring its importance in promoting well‐being among vulnerable groups. This research provides a culturally validated tool for measuring forgiveness and illuminates its health benefits, emphasizing its significance for diverse populations.