The positive effect of the Rotterdam Prostate Cancer Risk Calculator (RPCRC)-3/4 and RPCRC-MRI has already been confirmed. Nevertheless, its performance and applicability in clinical practice are still questioned. This study performs an external validation of the RPCRC-3/4 and -MRI within a Dutch clinical high-risk cohort. Men (n = 1,575) subjected to prostate biopsies between 2018 and 2021 due to a clinical suspicion of prostate cancer (PCa) were retrospectively included. PCa and clinically significant PCa (csPCa) were diagnosed in 996/1,575 (63.2%) and 656/1,575 (41.7%) men, respectively. The analysis showed that the RPCRC-3/4 underestimates the risk of csPCa within this Dutch high-risk clinical cohort: even though the RPCRC-3/4 could have prevented 37.3% of all MRIs, 18.3% of csPCa diagnoses would have been consequently missed. Recalibration of this risk calculator and adjustment of its risk thresholds was therefore indicated. The RPCRC-MRI, on the other hand, performed adequately and recalibration was not necessary.