Evidence suggests that benefits management is critical for enabling greater value and for enhancing the positive impact of programs, projects, and portfolios. However, many organizations only focus their efforts on identifying the intended benefits, without conducting a proper follow-up through ongoing assessment or evaluation to ensure benefits realization. For this reason, this study aims to obtain an overview of the actual use of the assessment methods in benefits management, through a compilation and analysis of the literature following the Systematic Mapping Study methodology. The results and findings obtained show a significant gap in the interplay between the fields of assessment methods and benefits management. Based on this, we suggest opportunities for improvement, such as developing audit guides and frameworks for enhancing the monitoring of the benefits, strengthening the focus on external benefits of organizations, and for adapting benefits assessment to the changed perceptions of intended benefits, in line with continuous improvement.