In over 50 countries, the 2nd leading cause of death after cardiovascular disease is cancer. Indeed, the 10th most diagnosed cancer worldwide is bladder cancer, with approximately half a million new reported cases with fifty percent of deaths per year. While cancer is primarily regarded because of host genetics and environmental influences, microorganisms are linked to 20% of human cancers. The microbiota of each individual is unique, undergoing development in childhood and adulthood, inhabiting the human body in various sites exposed to the external environment, including the gastrointestinal tract, oral cavity, genitourinary tract, and skin. The composition of the urinary microbiota can act as a host protection mechanism, preventing infections when the physiological balance is maintained, or allowing infection and colonization by pathogens when the balance is disturbed by factors related to the host or the environment. It was previously assumed that healthy individuals had sterile urine using culture-based methods. However, using high-throughput DNA sequencing and improved culture techniques, numerous microorganisms are discovered in the urine of healthy persons, many of which are not detectable by standard culture techniques. So, the symbiotic relationship between humans and commensal microbiota has become a topic of interest in both basic and clinical fields all over the world. This review will discuss the epidemiology and external risk factors of bladder cancer, as well as the association between urinary microbiota and urinary tract disorders and bladder cancer, besides their role in treatment.