Poor graft survival is a critical obstacle toward production of clinically relevant engineered tissues. Here we utilize a multicellular culturing approach for induction of vascular networks embedded within cardiac tissue constructs. The construct is composed of human cardiomyocytes, endothelial cells (ECs), and embryonic fibroblast cells co-seeded onto highly porous three-dimensional (3D) scaffolds. The resulting vascularized cardiac constructs showed microstructural details characteristic of cardiomyocytes and nascent vessels and exhibited synchronous beating activity in vitro. Upon implantation, stable grafts were formed presenting intense vascularization, with evidence of anastomosis between the pre-formed endothelial capillaries and host neovessels.