Background With the global ageing population, enhancing older adults’ engagement with health-related information and decisions has become increasingly important. Health literacy and beliefs about medicines reflect how older adults understand and interact with health-related concepts and interventions. However, there is limited synthesis of validated tools to assess these constructs in older adults. Aim To systematically review and identify validated tools for assessing health literacy and beliefs about medicines among older adults. Method A systematic search was conducted in PubMed, EMBASE, CINAHL, and PsycINFO. Studies were included if they: (1) involved participants aged ≥ 65 years, (2) used validated tools to assess health literacy or beliefs about medicines, and (3) reported outcomes related to these measures or their associations with other concepts. Study selection, data extraction, and quality assessment were performed independently by two investigators. Data were summarized using tabular and narrative synthesis. Result A total of 46 studies were included, comprising 13 instrument development studies and 28 cross-sectional studies. Eight instruments assessed general health literacy, four assessed eHealth literacy. Beliefs about medicines were only measured using the Beliefs about Medicines Questionnaire (BMQ) in cross-sectional studies. Across studies, health literacy has the potential to be translated or new questionnaires developed. Conclusion This review found that instruments used assessing health literacy in older adults are limited in scope and availability, with a notable lack of validated tools for measuring beliefs about medicines. Future research should prioritize the development of more generalizable health literacy questionnaire and consider adapting the BMQ for older adults.