The relationship between frailty and socioeconomic status has been widely explored in the literature. A deeper understanding toward the underlying mechanism is required to further assist policy makers in reducing the inequalities. The objective of this study is to systematically review evidence investigating the direct relationship between frailty and socioeconomic status. The review was conducted following the principles of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). [https://doi.org/10.4081/jphr.2021.2036]