A microfluidic platform integrating functional vascularized organoids-on-chip has been developed to enable long-term culture of three-dimensional cell aggregates such as spheroids, organoids, tumoroids, or tissue explants. This platform allows for the establishment and monitoring of endothelial networks around mesenchymal and pancreatic islet spheroids, as well as blood vessel organoids generated from pluripotent stem cells, cultured for up to 30 days on-chip. The networks establish functional connections with the endothelium-rich spheroids and vascular organoids, providing intravascular perfusion to these structures. Organoid growth, maturation, and function are enhanced when cultured on-chip using this vascularization method. This microphysiological system represents a viable organ-on-chip model to vascularize diverse biological 3D tissues and sets the stage to establish organoid perfusions using advanced microfluidics. The ability to vascularize organoids remains a challenge in tissue engineering. Most tissues exceeding 400 μm in thickness need a functional vasculature to ensure a sufficient supply of nutrients and oxygen, as well as the ability to remove carbon dioxide and cellular waste products, preventing the formation of necrotic inner cores. Although significant efforts have been directed towards creating increasingly complex organoid model systems in vitro, it remains necessary to transplant such organoids into host animals to establish functional vascular circulation. However, in vivo transplantations are very expensive and lack scalability for larger scale toxicity or drug screening. Considerable effort has been directed towards addressing this problem through the generation of perfusable vascular networks on-chip, either as standalone or by incorporation of other tissues to develop functional, vascularized organs-on-chips. In this in vitro approach, endothelial cells and supportive cells are seeded into a central microfluidic chamber using hydrogels. These hydrogels provide structural support to the embedded cells where they can self-organize into endothelial networks. The media flows continuously into the lateral channels adjacent to the central microchamber, providing the nutrients and gas exchange required for long-term cell culture. However, this conventional geometry does not allow reproduction of the fluxes observed in vivo, and replicating the in vivo functional vascularization of iPSC-derived organoids is still an ongoing challenge. Here, we report a platform to vascularize various biological tissues on-chip, using an original and user-friendly microfluidic device and chip loading process. The reliability of our system was validated using spheroids generated from human fibroblasts and endothelial cells as well as 3D human blood vessel organoids (BVOs) generated from human-induced pluripotent stem cells (hiPSCs) and human pancreatic islet spheroids. Importantly, we demonstrate effective anastomosis and controlled perfusion of the vascular organoids, as well as enhanced organoid growth, maturation, and vasculature development. Additionally, we reportA microfluidic platform integrating functional vascularized organoids-on-chip has been developed to enable long-term culture of three-dimensional cell aggregates such as spheroids, organoids, tumoroids, or tissue explants. This platform allows for the establishment and monitoring of endothelial networks around mesenchymal and pancreatic islet spheroids, as well as blood vessel organoids generated from pluripotent stem cells, cultured for up to 30 days on-chip. The networks establish functional connections with the endothelium-rich spheroids and vascular organoids, providing intravascular perfusion to these structures. Organoid growth, maturation, and function are enhanced when cultured on-chip using this vascularization method. This microphysiological system represents a viable organ-on-chip model to vascularize diverse biological 3D tissues and sets the stage to establish organoid perfusions using advanced microfluidics. The ability to vascularize organoids remains a challenge in tissue engineering. Most tissues exceeding 400 μm in thickness need a functional vasculature to ensure a sufficient supply of nutrients and oxygen, as well as the ability to remove carbon dioxide and cellular waste products, preventing the formation of necrotic inner cores. Although significant efforts have been directed towards creating increasingly complex organoid model systems in vitro, it remains necessary to transplant such organoids into host animals to establish functional vascular circulation. However, in vivo transplantations are very expensive and lack scalability for larger scale toxicity or drug screening. Considerable effort has been directed towards addressing this problem through the generation of perfusable vascular networks on-chip, either as standalone or by incorporation of other tissues to develop functional, vascularized organs-on-chips. In this in vitro approach, endothelial cells and supportive cells are seeded into a central microfluidic chamber using hydrogels. These hydrogels provide structural support to the embedded cells where they can self-organize into endothelial networks. The media flows continuously into the lateral channels adjacent to the central microchamber, providing the nutrients and gas exchange required for long-term cell culture. However, this conventional geometry does not allow reproduction of the fluxes observed in vivo, and replicating the in vivo functional vascularization of iPSC-derived organoids is still an ongoing challenge. Here, we report a platform to vascularize various biological tissues on-chip, using an original and user-friendly microfluidic device and chip loading process. The reliability of our system was validated using spheroids generated from human fibroblasts and endothelial cells as well as 3D human blood vessel organoids (BVOs) generated from human-induced pluripotent stem cells (hiPSCs) and human pancreatic islet spheroids. Importantly, we demonstrate effective anastomosis and controlled perfusion of the vascular organoids, as well as enhanced organoid growth, maturation, and vasculature development. Additionally, we report