Objective To investigate the effect of monocyte count to high density lipoprotein ratio (MHR) on early complications after off-pump coronary artery bypass grafting and to explore the predictive factors for early complications in patients after off-pump coronary artery bypass grafting. Methods The clinical data of patients who underwent simple off-pump coronary artery bypass grafting from October 2021 to September 2023 in our hospital were retrospectively analyzed. The patients were divided into a low value group and a high value group according to the median MHR value. The clinical data of the two groups were compared, and binary logistic regression analysis was used to explore the and predictors of atrial fibrillation (AF) and acute kidney injury (AKI) after coronary artery bypass grafting. Results A total of 220 patients were included, with a median MHR of 0.48. There were 108 patients in the low value group (MHR<0.48), including 71 males and 37 females, with an average age of 65.28±7.85 years. There were 112 patients in the high-value group (MHR≥0.48), including 84 males and 28 females, with an average age of 64.57±8.75 years. There was no statistical difference between the two groups in terms of general basic data such as gender or age (P>0.05). The incidence of postoperative AF and AKI in the high-value group was significantly higher than that in the low-value group (P<0.05), and no statistical difference in terms of other postoperative complications was observed. Binary logistic regression analysis showed that MHR was a risk factor for postoperative AKI and postoperative AF (P<0.05). Conclusion The study shows that MHR is a risk factor for new-onset AF and AKI after coronary artery bypass grafting.