The high morbidity and mortality of bladder cancer highlights the need of cancer risk prediction, which can be achieved by the analysis of the related DNA mutations. The facile, low-cost colorimetric methods were promising but still suffered from low sensitivity or poor selectivity. Therefore, highly active colorimetric probes and DNA/signal amplification technologies are still in urgent need to be explored. Herein, a bimetallic nanozyme Fe2MoO4 NPs with excellent peroxidase-like activity were successfully synthesized as the colorimetric probe, combining with hybridization chain reaction (HCR) to analyze the PSCA rs2294008 (C > T) as a factor for risk prediction of bladder cancer. The absorbance variation and selectivity can then be amplified upon the HCR, which could lead to prolonged DNA length beyond the range of •OH action and double chain with more negative charge to occupy more TMB while repelling the negatively charged nanozyme. Under the optimized conditions, the as-proposed method can achieve sensitive detection of the DNA mutation in the concentration range of 25 pM to 4 nM and detection limit as low as 2 pM, which is superior or comparable to most previously reported colorimetric sensors. Moreover, the practicability of the sensor was verified via the application in serum samples, showing satisfactory accuracy and good reproducibility.