Brachytherapy remains a cornerstone in the treatment of genitourinary malignancies, offering a unique advantage of delivering highly focused radiation doses directly to the tumor site. Its ability to limit exposure to surrounding healthy tissues makes it particularly valuable in organ-preserving strategies. This chapter provides a comprehensive overview of the current role of brachytherapy in managing prostate, penile, urethral, and bladder cancers. It outlines patient selection criteria, procedural techniques, dosimetric planning, and toxicity profiles, supported by evidence-based recommendations and clinical experience. With evolving technologies and growing emphasis on quality of life, brachytherapy continues to hold a vital place in modern urologic oncology.