Prostate cancer remains one of the most prevalent malignancies among men worldwide, necessitating the development of rapid, sensitive, and reliable diagnostic methods. This chapter provides a comprehensive overview of biosensor systems developed for prostate cancer diagnosis, emphasizing their working principles, biomarker integration, and technological evolution. Key prostate cancer biomarkers—including prostate-specific antigen (PSA), PCA3, TMPRSS2-ERG gene fusion, microRNAs, sarcosine, and creatine kinase—are discussed in detail, highlighting their clinical relevance and application in biosensing platforms. The chapter also explores recent advancements in biosensor technologies, ranging from electrochemical and optical sensors to cutting-edge CRISPR/Cas-based, artificial intelligence (AI)-integrated, and smartphone-enabled biosensors. Particular attention is given to the design innovations that enhance sensitivity, specificity, and usability. Biosensors are anticipated to substantially improve the accuracy and availability of prostate cancer diagnoses, facilitating early intervention and superior patient outcomes.