Key points A reduction in Kindlin‐2 levels in endothelial cells compromises vascular barrier function. Kindlin‐2 is a previously unrecognized component of endothelial adherens junctions. By interacting directly and simultaneously with β‐ or γ‐catenin and cortical actin filaments, Kindlin‐2 stabilizes adherens junctions. The Kindlin‐2 binding sites for β‐ and γ‐catenin reside within its F1 and F3 subdomains. Although Kindlin‐2 does not associate directly with tight junctions, its downregulation also destabilizes these junctions. Thus, impairment of both adherens and tight junctions may contribute to enhanced leakiness of vasculature in Kindlin‐2+/− mice. Abstract Endothelial cells (EC) establish a physical barrier between the blood and surrounding tissue. Impairment of this barrier can occur during inflammation, ischaemia or sepsis and cause severe organ dysfunction. Kindlin‐2, which is primarily recognized as a focal adhesion protein in EC, was not anticipated to have a role in vascular barrier. We tested the role of Kindlin‐2 in regulating vascular integrity using several different approaches to decrease Kindlin‐2 levels in EC. Reduced levels of Kindlin‐2 in Kindlin‐2+/– mice aortic endothelial cells (MAECs) from these mice, and human umbilical ECs (HUVEC) treated with Kindlin‐2 siRNA showed enhanced basal and platelet‐activating factor (PAF) or lipopolysaccharide‐stimulated vascular leakage compared to wild‐type (WT) counterparts. PAF preferentially disrupted the Kindlin‐2+/− MAECs barrier to BSA and dextran and reduced transendothelial resistance compared to WT cells. Kindlin‐2 co‐localized and co‐immunoprecipitated with vascular endothelial cadherin‐based complexes, including β‐ and γ‐catenin and actin, components of adherens junctions (AJ). Direct interaction of Kindlin‐2 with β‐ and γ‐catenin and actin was demonstrated in co‐immunoprecipitation and surface plasmon resonance experiments. In thrombin‐stimulated HUVECs, Kindlin‐2 and cortical actin dissociated from stable AJs and redistributed to radial actin stress fibres of remodelling focal AJs. The β‐ and γ‐catenin binding site resides within the F1 and F3 subdomains of Kindlin‐2 but not the integrin binding site in F3. These results establish a previously unrecognized and vital role of Kindlin‐2 with respect to maintaining the vascular barrier by linking Vascuar endothelial cadherin‐based complexes to cortical actin and thereby stabilizing AJ.