As cities confront multiple challenges such as climate change, urbanization, and food security, growing attention has been given to sustainable vertical farming and renewable energy solutions. Building facades, typically underutilized in high-density urban environments, present an opportunity for multifunctional buildings composed of both photovoltaic (PV) systems and vertical farming modules. However, on vertical surfaces, these two systems often compete for space. This research focuses on the development of a multifunctional agrivoltaics building envelope (ABE) system, combining building-integrated PV (BIPV) technology with hydroponic vertical farming. This ABE system adopts a modular design approach, where each unit can be prefabricated independently and assembled through an interlocking connection design and bolted fastening to ensure ease of construction and scalability. The design process includes the development of 2D cross-sectional technical design, assembly sequences, and an analysis of key design parameters through 3D modeling. The research adopts a combined Research through Design (RtD) and Research for Design (RfD) approach to bridge prototyping, testing, and performance optimization. This research highlights the potential of integrating renewable energy with agricultural production in building envelope systems. By addressing space optimization and multifunctionality, the research provides a practical framework for future applications in urban sustainability.