Background: A pretreatment risk stratification of prostate cancer (PCa) is important for determining appropriate treatment option and prognostic prediction. Although numerous quantifiable approaches can provide fundamental insights in PCa, a clinical tool should leverage the integration of all data representations to enables detailed assessment. We developed a generalizable machine learning platform, designated PI-Risk, which incorporates clinicians’ prior identifications with deep transferrable imaging feature representations into predictive models for PCa Gleason grade. Methods: A retrospective study included 1442 biopsy-naïve patients from two tertiary care medical centers between January 2014 and December 2019. Model performance was typically evaluated against a “ground truth” with imaging-histopathologic annotations using receiver operating characteristic (ROC). Detection rates such as true positive, true negative, false positive and false negative rate were reported using a confusion matrix analysis. The Cox model’s performance was evaluated based on Harrell’s concordance index (C-index), calibration curves and Kaplan–Meier survival analysis. Results: In multinomial regression analyzing model, predicted IntraT-Rad G0 (odds ratio [OR], 3.01; 95% confidence intervals [CIs], 2.74–3.34, p < 0.001) and PI-RADS score 2 (OR, 2.88; 95% CIs, 2.47–3.17, p = 0.002) were two independent predictors of G0 stage. Predicted IntraT-Rad G1 (OR, 2.42; 95% CIs, 2.13–2.86, p < 0.001) and PSA 4-10 ng/ml (OR, 1.29; 95% CIs, 1.06–1.43, p = 0.037) were two independent predictors of G1 stage. PSA 10-20 ng/ml (OR, 1.52; 95% CIs, 1.32–1.67, p = 0.005), Predicted PeriT-DLR-SqueezeNet G1 (OR, 1.31; 95% CIs, 1.14–1.52, p = 0.009) and Predicted IntraT-Rad G3 (OR, 1.29; 95% CIs, 1.07–1.44, p = 0.011) were three independent predictors of G2 stage. PI-RADS score 5 (OR, 1.84; 95% CIs, 1.74–2.31, p < 0.001) were the independent predictor of G3 stage. PI-RADS score 5 (OR, 2.84; 95% CIs, 2.62–3.17, p < 0.001) and PSA > 100 ng/ml (OR, 1.69; 95% CIs, 1.36–1.83, p = 0.007) were two independent predictors of G4 stage. And the multivariate Cox analysis model shows that, among the 5 pretreatment risk factors (age, PSA, PCa location, PI-RADS score and PI-Risk score), PSA ≥ 20 ng/ml (OR, 1.58; 95% CI, 1.20-2.08; p = 0.001) and PI-Risk ≥ G3 (OR, 1.45; 95% CI, 1.12-1.88; p = 0.005) were the independent predictors of BCR.Conclusions: We concluded that the PI-Risk can offer a noninvasive alternative tool to stratify PCa aggressiveness. This enables a step towards PCa risk stratification.