Mechanical and biochemical signals play important roles in development and disease. Plasma membrane acts as a mechanochemical transducer to mediate vital processes. We wondered how mammalian cells can regulate their plasma membrane tension in response to osmosis and its interplay with cell volume regulation. We demonstrate the existence of a coupling between plasma membrane tension and cell volume well described by passive physical mechanisms. To understand the role of biochemical signals, we depleted caveolae and inhibited ion transporters and channels, mTORCs, and the cytoskeleton to prove that this coupling is regulated by the excess membrane buffer and is thus partially independent of specific regulatory mechanisms of tension and volume. Additionally, we observed that cell volume and plasma membrane tension coupling is maintained even after multiple cycles of osmotic shocks. Altogether, these findings underlie the robustness of the coupling between plasma membrane tension and cell volume.