Polypharmacy is common in older people who often live with disability and dependency. The number of older people living with unmet needs for social care is also believed to be rising. Polypharmacy is simple to operationalise, whilst unmet needs are not routinely identified but are known to adversely affect health and well-being. Therefore, this systematic review aimed to investigate whether polypharmacy is a marker of unmet needs for social care in older people. Sixteen databases were searched from inception to January 2021. Studies were included if they reported quantitative data for polypharmacy (“multiple medicines”) in relation to unmet needs for social care (“relative or absolute”) in older people (“study criteria aged ≥55 years or mean age ≥55 in the sample as a whole or stratified data for the ≥55-year age group”) and were from a high-income country (defined by the World Bank). Quality was assessed using the National Institute for Health tool for observational studies. Four studies were identified from 2,549 citations, and overall, the quality of evidence was low. Some older people using multiple medications had their social care needs met, whilst others did not. However, there is a clear rationale as to why polypharmacy may be linked to unmet social care needs. Given the limited studies identified in this review, future research should explore this further. The type of unmet need measure may be important to understand the nature of the relationship between the use of multiple medications and unmet social care needs.