Three-dimensional (3D) bioreactor systems are essential for vascular tissue engineering as they provide controlled environments that better mimic physiological conditions compared to static culture systems. In this study, an IoT-enabled modular rotating 3D bioreactor platform was designed, fabricated using Fused Deposition Modeling (FDM), and biologically validated. The system integrates a Wi-Fi-supported ESP8266 controller and a touchscreen human–machine interface (HMI), enabling real-time monitoring and remote operation. Agarose-chitosan-based tubular hydrogel constructs were seeded with human aortic smooth muscle cells (HASMCs) and cultured under dynamic conditions for 14 days. Biocompatibility was assessed using a lactate dehydrogenase (LDH) assay, while cellular distribution and mitochondrial activity were evaluated by confocal microscopy using DAPI and MitoTracker staining. Fluorescence intensity was further quantified using ImageJ, and 3D surface plots were generated to visualize spatial signal distribution. The results demonstrated sustained cell viability with decreasing cytotoxicity over time. Confocal analysis confirmed a homogeneous distribution of cells within the hydrogel matrix, and quantitative fluorescence analysis showed significantly higher MitoTracker intensity compared to DAPI, indicating increased metabolic activity under dynamic conditions. These findings suggest that the developed bioreactor provides a stable, controllable, and effective platform for vascular tissue engineering applications.