Existing studies on the mechanism of cell volume regulation are mainly relevant to ion channels and osmosis in extracellular fluid. Recently, accumulating evidence has shown that cellular mechanical microenvironment also influences the cell volume. Herein, we investigated the regulation of substrate stiffness on the cell volume homeostasis of MCF‐7 cells and their following migration behaviors. We found that cell volume increases with increasing substrate stiffness, which could be affected by blocking the cell membrane anion permeability and dopamine receptor. In addition, the cell migration is significantly inhibited by decreasing the cell volume using tamoxifen and such inhibition effect on migration is enhanced by increasing substrate stiffness. The cell membrane anion permeability might be the linker between cellular mechanical microenvironment and cellular volume homeostasis regulation. This work revealed the regulation of substrate stiffness on cell volume homeostasis for the first time, which would provide a new perspective into the understanding of cancer metastasis and a promising anti‐cancer therapy through regulation of cell volume homeostasis. This work revealed the regulation of substrate stiffness on cell volume homeostasis for the first time, which could be affected by blocking the cell membrane anion permeability and dopamine receptor. In addition, the cell migration is significantly inhibited by decreasing the cell volume using tamoxifen and such inhibition effect on migration is enhanced by increasing substrate stiffness.