Magnetic resonance spectroscopy (MRSI) can distinguish between benign and malignant prostate diseases. This study investigated the potential of MRSI for diagnosing prostate cancer and guiding prostate biopsy. We retrospectively reviewed 234 patients with suspected prostate cancer who underwent MRSI with targeted prostate biopsy. Patients were divided into two groups according to their puncture pathology: prostate cancer (n = 103, 44.02%) and benign prostatic disease (n = 131, 55.98%). The t-test, Mann-Whitney U test, or chi-square test was used to compare the groups. The diagnostic abilities of MRSI, prostate-specific antigen level, digital rectal examination, and magnetic resonance imaging without contrast for prostate cancer were compared using the area under the receiver operating characteristic curve (AUC-ROC); the ARC-ROC values were 0.831, 0.768, 0.692, and 0.656, respectively. The AUC-ROC value for diagnosing prostate cancer using the CC/c ratio was 0.853. CC/c ratio > 0.97 was identified as the optimal threshold for diagnosing prostate cancer (sensitivity, 86.5%; specificity, 78.6%; Youden index, 0.651). Spearman correlation analysis revealed a correlation between the CC/c ratio and Gleason score (r = 0.737, p < 0.001). Using the CC/c ratio of MRSI as an adjunct to targeted prostate biopsy can improve the detection rate of positive biopsies and evaluate prostate cancer invasiveness.