Organoids, three-dimensional structures derived from stem cells, offer unique advantages for studying organ development, disease modeling, and drug screening. However, their translational potential is limited by the lack of an integrated vascular network. Bioengineering strategies are rapidly advancing to enable efficient vascularization of organoids, including co-culturing with vascular cells, co-culturing with vascular organoids, co-differentiating stem cells into vascular lineages, using organoid-on-a-chip technology, and 3D bioprinting. This review explores the field of organoid vascularization, examining the biological principles that inform bioengineering approaches. It also envisions how the convergence of stem cell biology, biomaterials, and advanced fabrication technologies will propel the creation of increasingly sophisticated organoid models, accelerating biomedical discoveries and innovations. Organoids recapitulate critical aspects of in vivo organ complexities and functionalities under specific physical and signaling cues. However, vascularization is crucial for organoid viability, as it facilitates oxygen delivery, nutrient transport, and metabolic waste removal. While diffusion remains efficient for smaller organoids, it is inadequate beyond a specific size. The diffusion limit of oxygen and nutrients in mammalian tissues is approximately 100–200 μm, imposing significant physical constraints on the growth and longevity of larger constructs. In the absence of a functional vasculature, core regions of larger organoids often suffer from hypoxia and reduced nutrient access, resulting in necrosis and impaired functionality. Thus, engineering intricate vascular networks within these 3D organoid structures is vital to fully realize their therapeutic use. Bioengineering strategies offer promising solutions to address the challenge of organoid vascularization. These include co-culturing with vascular cells, co-culturing with vascular organoids, organoid co-differentiation, organoid-on-a-chip platforms, and organoid 3D bioprinting. These methods enable the integration of perfusable vasculature within organoids, offering enhanced physiological relevance. The review also discusses the biological principles of vascular biology, including the role of microvessels, stem cell niches, and the influence of fluid shear stress on vascularization. It highlights the importance of understanding the interplay between signaling gradients and spatiotemporal dynamics in distinguishing vasculogenesis from angiogenesis. The review further explores the use of scaffolds for engineering vascularization, including naturally derived and synthetic hydrogels, which provide mechanical support and a rich signaling environment for embedded cells and sprouting vessels. The use of hPSCs for creating vascularized organoids is also discussed, highlighting their potential for regenerative medicine and disease modeling. The review concludes by emphasizing the importance of integrating insights from developmental biology, material science, and bioengineering to overcome the challenges in replicating complex vascular networks and achieving physiologically relevant vascular structures within organoids.Organoids, three-dimensional structures derived from stem cells, offer unique advantages for studying organ development, disease modeling, and drug screening. However, their translational potential is limited by the lack of an integrated vascular network. Bioengineering strategies are rapidly advancing to enable efficient vascularization of organoids, including co-culturing with vascular cells, co-culturing with vascular organoids, co-differentiating stem cells into vascular lineages, using organoid-on-a-chip technology, and 3D bioprinting. This review explores the field of organoid vascularization, examining the biological principles that inform bioengineering approaches. It also envisions how the convergence of stem cell biology, biomaterials, and advanced fabrication technologies will propel the creation of increasingly sophisticated organoid models, accelerating biomedical discoveries and innovations. Organoids recapitulate critical aspects of in vivo organ complexities and functionalities under specific physical and signaling cues. However, vascularization is crucial for organoid viability, as it facilitates oxygen delivery, nutrient transport, and metabolic waste removal. While diffusion remains efficient for smaller organoids, it is inadequate beyond a specific size. The diffusion limit of oxygen and nutrients in mammalian tissues is approximately 100–200 μm, imposing significant physical constraints on the growth and longevity of larger constructs. In the absence of a functional vasculature, core regions of larger organoids often suffer from hypoxia and reduced nutrient access, resulting in necrosis and impaired functionality. Thus, engineering intricate vascular networks within these 3D organoid structures is vital to fully realize their therapeutic use. Bioengineering strategies offer promising solutions to address the challenge of organoid vascularization. These include co-culturing with vascular cells, co-culturing with vascular organoids, organoid co-differentiation, organoid-on-a-chip platforms, and organoid 3D bioprinting. These methods enable the integration of perfusable vasculature within organoids, offering enhanced physiological relevance. The review also discusses the biological principles of vascular biology, including the role of microvessels, stem cell niches, and the influence of fluid shear stress on vascularization. It highlights the importance of understanding the interplay between signaling gradients and spatiotemporal dynamics in distinguishing vasculogenesis from angiogenesis. The review further explores the use of scaffolds for engineering vascularization, including naturally derived and synthetic hydrogels, which provide mechanical support and a rich signaling environment for embedded cells and sprouting vessels. The use of hPSCs for creating vascularized organoids is also discussed, highlighting their potential for regenerative medicine and disease modeling. The review concludes by emphasizing the importance of integrating insights from developmental biology, material science, and bioengineering to overcome the challenges in replicating complex vascular networks and achieving physiologically relevant vascular structures within organoids.