Significance We show that vascular pericytes significantly contribute to cancer invasion and metastasis by the mechanism of the pericyte–fibroblast transition (PFT). This study proposes this concept and indicates the vascular pericyte’s role. Vascular pericytes were considered to remodel tumor vessels toward a mature phenotype. However, once dissociated from tumor vessels their functions within the tumor tissue are not known. In the present study, we show that pericytes, once detached from tumor microvasculatures, underwent differentiation to become stromal fibroblasts, which are known to contribute to tumor invasion and metastasis. Our results show that vascular pericytes are the important source of stromal fibroblasts and targeting PFT may offer a new treatment option in cancer metastasis.