This study explored the conceptual constructs of consumer benefits and perceived risks of online fashion rental services (Online FRS) and their impacts on usage intention towards Online FRS. The mediating roles of perceived risks and service trust were examined in this research. A survey was performed on female shoppers between the ages of 20–30 residing in a metropolitan area. Results of this research were as follows: (1) The results analyzing the sub-dimension of benefits (Reasonable cost, Wearing at right time, place and occasion (TPO), Space Saving, Entertaining, Product Variety, Style Conformity) and perceived risks (Financial, Performance, Social) clearly presented factorial structures. (2) Reasonable cost, Style Conformity, and Product Variety showed significantly positive influences on usage intentions towards online fashion rental services; in addition, Financial, Performance, and Social risks of rental services had a negative effect on usage intentions. (3) Service trust and consumer perceptions of Financial and Performance risks had important mediating roles in the relationship between consumer benefits and usage intentions towards Online FRS. This study highlighted that consumer benefits, perceived risks, and service trust should be registered among consumers to boost usage intentions towards Online FRS.