Health-related quality of life (HRQOL) is a multifactorial concept in assessing physical and mental health. This study was performed to evaluate the HRQOL of patients undergoing coronary artery bypass graft (CABG) surgery and the predictors of HRQOL in patients until 1 year after surgery. This cross-sectional study included 110 consecutive patients who underwent elective CABG in a medical center in South Korea. The Short-Form Health Survey, cardiac symptom survey, cardiac self-efficacy, and the Interpersonal Support Evaluation List-12 were used to measure the HRQOL, symptom experience, self-efficacy, and social support, respectively. The regression model explained 42% of the variance in the participants' physical HRQOL. The predictors of the physical HRQOL include the presence of a spouse, post-CABG duration, symptom experience, and self-efficacy. The regression model explained 36% of the variance in the participants' mental HRQOL. The predictors of the mental HRQOL included perceived health status, self-efficacy, and social support. The predictive factors for HRQOL after CABG were the presence of a spouse, post-CABG duration, symptom experience, self-efficacy, and social support. Furthermore, a suitable program and nursing interventions could be implemented to improve the HRQOL of post-CABG patients.