Aims/Background Primary hypercholesterolemia (PHC) is a major risk factor for atherosclerotic cardiovascular disease (ASCVD). Although the fact that statins effectively lower low-density lipoprotein cholesterol (LDL-C) levels, some patients fail to achieve target LDL-C levels and continue to have a high risk of cardiovascular disease. This study aims to evaluate the clinical efficacy and safety of ezetimibe combined with rosuvastatin in patients with PHC. Methods This study retrospectively examined 101 patients with PHC who received statins at the cardiology department of Jilin Province FAW General Hospital, between 2021 and 2024. Patients were divided into the observation (ezetimibe combined with rosuvastatin, n = 45) and control (rosuvastatin, n = 66) groups in accordance with their treatment regimens. Data were sourced from the hospital's electronic health records system, and statistical analysis was performed by using SPSS 25.0 software (IBM Corporation, Armonk, NY, USA). Results Baseline characteristics were similar between the two groups. After 12 weeks of treatment, the reduction in LDL-C levels in the observation group (–0.373 [–0.427, –0.348]) was greater than that in the control group (–0.240 [–0.318, –0.222], p < 0.001). The percentage changes in total cholesterol (TC), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C) levels were significantly better in the observation group (TC: –0.230 [–0.302, –0.144], TG: –0.292 [–0.333, –0.237], and HDL-C: 0.081 [0.067, 0.111]) than in the control group (TC: –0.127 [–0.158, –0.119], TG: –0.082 [–0.101, –0.067], and HDL-C: 0.000 [–0.163, 0.133] with p < 0.001, p < 0.001, and p = 0.011, respectively). Regarding drug safety, the incidence of adverse events was comparable between the two groups (11.10% vs. 12.10%, p = 0.871). Conclusion The combination of ezetimibe and rosuvastatin demonstrates superior lipid-lowering efficacy and good safety in patients with PHC inadequately controlled by statin therapy, providing an effective alternative treatment option. Further large-scale, multicenter randomized controlled trials are warranted to confirm its long-term efficacy and safety.