Objectives: Work-related stress (WRS) is significantly associated with health-related quality of life (HRQoL), but the amounts of evidence on differences of effort-reward imbalance (ERI) and job strain index (JSI) remain sparse and have limited generalizability. Therefore, we aimed to assess the association between ERI and JSI with HRQoL and assess the mediation effect of social support (JS) and over-commitment (OC) on this association in Taiwan’s civil servants. Material and Methods: A cross-sectional national survey was given to registered civil servants in Taiwan – 20 046 civil servants from 647 institutions were enrolled using multistage stratified random cluster sampling. A web-questionnaire collected demographic information, job characteristics, and different indexes of ERI and job-control-demand-support (JCDS) models. Structural equation model (SEM) was used to examine the association between ERI and JSI with HRQoL, and the mediation effect of JS and OC on the associations. Results: In the ERI model, ERI and OC were consistently negatively associated with the mental component score (MCS) (r = –0.46 and r = –0.37) and physical component score (PCS) (r = –0.45 and r = –0.34), which were higher than job demand (r = –0.28 and r = –0.22) and JSI (r = –0.38 and r = –0.29). Using hierarchical multiple regression analyses, ERI was significantly correlated with MCS and PCS, which was consistently higher than JSI. The ERI and JSI were significantly correlated with MCS (β = –0.170 and β = –0.140) and PCS (β = –0.150 and β = –0.082) using SEM analysis, whereas ERI was considerably higher than in JSI. In addition, OC and JS mediated the association between The ERI and JSI with HRQoL. Conclusions: We found the ERI index is significantly correlated with HRQoL superior to JSI, in particular among Taiwan civil servants. Further longitudinal studies are needed to determine the causality and spatiotemporal relation of these differences. Int J Occup Med Environ Health. 2022;35(4):425–36