Spatiotemporally controlled growth factor (GF) delivery is crucial for achieving functional vasculature within engineered tissues. However, conventional GF delivery systems show inability to recapitulate the dynamic and heterogeneous nature of developing tissue's biochemical microenvironment. Herein, an aptamer-based programmable GF delivery platform is described that harnesses dynamic affinity interactions for facilitating spatiotemporal control over vascular endothelial GF (VEGF165) bioavailability within gelatin methacryloyl matrices. The platform showcases localized VEGF165 sequestration from the culture medium (offering spatial-control) and leverages aptamer-complementary sequence (CS) hybridization for triggering VEGF165 release (offering temporal-control), without non-specific leakage. Furthermore, extensive 3D co-culture studies (human umbilical vein-derived endothelial cells & mesenchymal stromal cells), in bi-phasic hydrogel systems revealed its fundamentally novel capability to selectively guide cell responses and manipulate lumen-like microvascular networks via spatiotemporally controlling VEGF165 bioavailability within 3D microenvironment. This platform utilizes CS as an external biochemical trigger for guiding vascular morphogenesis which is suitable for creating dynamically controlled engineered tissues.