Endothelial-to-mesenchymal transition (EndMT) is a dynamic, biological process in which endothelial cells (ECs) suppress fundamental endothelial properties and adopt mesenchymal characteristics such as the loss of cell-cell contacts, an increase in migratory potential, and increased contractility. Although this trans-differentiation program is recognized as essential for development and vascular homeostasis there is rising evidence of its incidence in vascular pathological conditions, particularly atherosclerosis, venous disease, and varicose veins. Therapeutic targeting of EndMT appears promising but in-vitro EndMT studies face numerous hurdles including the lack of standardized experimental models and the dynamic nature of endothelial plasticity. This study aims to directly quantify the physical forces behind EndMT progression to identify a mechanophenotype. To address these challenges, we performed immunofluorescence imaging of endothelial and mesenchymal-specific markers, morphological analysis, and measured tractions and intercellular stresses of venous endothelial cells exposed to TGF-β1, a known EndMT inducer, at 24, 48, and 72 hours. Interestingly, our time-point analysis revealed a decrease in tractions and intercellular stresses and increase in cell area and eccentricity at 24 hours followed by a decrease in endothelial markers and increase in mesenchymal markers via immunofluorescence at 48 and 72 hours. Additionally, our results revealed EndMT to occur gradually, with most cells progressing to an intermediate phenotype, however, a subpopulation of cells progressed to a more complete mesenchymal phenotype and prompted us to investigate the mechanics at the single-cell level. Our single-cell results revealed TGF-β1 treated cells yielded a 1.65-fold increase in tractions compared to control cells. The mechanics-oriented focus of this study is unique and complimentary to standard biochemical and molecular strategies used to study EndMT, which can offer new perspectives for innovative therapeutic interventions for endothelial dysfunction and vascular disease.