Microorganisms have evolved to thrive in virtually any terrestrial and marine environment, exposing them to various mechanical cues mainly generated by fluid flow and pressure as well as surface contact. Cellular components enable bacteria to sense and respond to physical cues to optimize their function, ultimately improving bacterial fitness. Owing to newly developed biophysical techniques, we are now starting to appreciate the breadth of bacterial phenotypes influenced by mechanical inputs: adhesion, motility, biofilm formation and pathogenicity. In this Review, we discuss how microbiology and biophysics are converging to advance our understanding of the mechanobiology of microorganisms. We first review the various physical forces that bacteria experience in their natural environments and describe the structures that transmit these forces to a cell. We then discuss how forces can provide feedback to enhance adhesion and motility and how they can be transduced by dedicated cellular machinery to regulate diverse phenotypes. Finally, we provide a perspective on how mechanics influence biofilm spatial organization and homeostasis.