Objective To investigate the diagnostic value and clinical efficacy of magnetic resonance imaging (MRI) combined with serum prostate-specific antigen (PSA) in prostate cancer. Methods The records of 95 patients, who were admitted to the Lu’an Fourth People’s Hospital, underwent prostate MRI and serum PSA testing and were confirmed diagnosis of prostate cancer by pathology, were retrospectively analysed from November 2022 to December 2024. According to the different pathological results, they were divided into prostate cancer group (n=42) and nonprostate cancer group (n=53). MRI images were evaluated using the PI-RADS v2.1 criteria, and a PI-RADS score ≥ 4 was determined as positive MRI. The serum PSA levels of the patients were also detected. The diagnostic efficacy and area under the curve (AUC) of MRI alone, PSA alone and the combination of the two were compared. Results Serum PSA levels were significantly higher in the prostate cancer group than in the non-cancer group [(45.98 ±18.76) ng/mL vs (6.83 ±4.34) ng/mL, P <0.05]. The combination of MRI and PSA approach showed significantly higher specificity and AUC compared to either MRI or PSA alone (0.931vs 0.849 vs 0.830, 0.932 vs 0.893 vs 0.817,both P=0.001). Conclusion The combination of MRI and serum PSA enhances diagnostic accuracy for prostate cancer, offering improved specificity and greater clinical value for early detection and differential diagnosis.