Updated project metadata. Tumor progression is often accompanied with increased extracellular matrix stiffness, but how this affects endothelial cells (ECs) is largely unknown. We used mass spectrometry to analyse the proteomic changes of primary human ECs cultured on physiological or tumor stiffness and found that CCN1/CYR61 is highly induced by tumor stiffness. Knock out of Ccn1 in the vasculature of Ccn1loxP/loxP mice by administrating a soluble form of Cre shows that fewer of the treated mice harbour circulating tumor cells and lung metastases, without affecting primary tumor growth, using the B16F10 syngeneic mouse melanoma model This demonstrates that CCN1 loss in the host impairs cancer metastasis and we dissected the molecular mechanism in vitro. Stiffness-induced CCN1 acts via (integrin αvβ3), FAK, beta-catenin signalling to increase N-Cadherin expression in ECs, which, in turn, leads to an elevated adhesion of cancer cells to ECs via N-Cadherin homophilic interactions.