Urinary tract infection (UTI) is one of the most common infectious diseases, with a global annual incidence of ~175 million cases. Uropathogenic Escherichia coli (UPEC) is the major cause of UTI (>80%) and increasingly associated with rising antibiotic resistance. UPEC form biofilms during infection of the urinary tract, either on the luminal surface of the bladder, intracellularly within bladder superficial epithelial cells, or on the surface of indwelling catheters. This lifestyle of sessile growth promotes enhanced resistance, persistence and increased rates of recurrent UTI. UPEC employ a range of virulence factors to form biofilms, including fimbrial adhesins for attachment and autotransporters to promote cell-to-cell aggregation. In addition, UPEC biofilms are encased in an extracellular matrix comprised of proteins such as curli amyloid fibres and polysaccharides such as cellulose, which together form a hydrating glue that provides structural support for the biofilm and protects its component cells. Here, we describe the key features of UPEC biofilms and their importance for UPEC pathogenesis of the urinary tract.