Prostate cancer (PCa) is the second most common malignancy in men worldwide. Despite advances in treatment, PCa often progresses to castration-resistant and chemo-resistant stages, underscoring the need for a deeper understanding of the tumour microenvironment (TME) and its regulatory mechanisms. The dynamic TME plays a pivotal role in PCa initiation, progression, and therapeutic response. In recent years, microRNAs (miRNAs) have emerged as critical regulators of gene expression within the TME, influencing cellular processes such as proliferation, angiogenesis, immune modulation, and metastasis. These small non-coding RNAs act either as oncogenic miRNAs (oncomiRs) promoting tumour growth or tumour suppressor miRNAs inhibiting tumour progression. This chapter explores the complex role of miRNAs in modulating various components of the PCa microenvironment, including cancer-associated fibroblasts (CAFs), tumour-associated macrophages (TAM), immune cells, extracellular matrix (ECM), angiogenesis, and hypoxia responses. Additionally, we discuss the epigenetic regulation of miRNA expression through DNA methylation and histone modifications, which further contribute to PCa pathogenesis. Finally, we evaluate the therapeutic potential of miRNA-based interventions, such as diagnostic biomarkers, mimics, and inhibitors, and outline current challenges in miRNA delivery, specificity, and clinical translation.