This thesis project, titled “Design and Testing of Plant-Fibre Composite Profiles for Structural Facade Applications”, addresses the limited development of non-wood plant-fibre composites into structural profiles for façade design, specifically mullions in stick-built curtain wall systems. It investigates whether these bio-based composites can be engineered into aluminium-like profiles that meet mechanical, environmental and regulatory requirements for low- and mid-rise buildings. Building on a literature review of plant fibres, polymer matrices, manufacturing techniques and curtain wall design principles, the research develops and tests multiple plant-fibre/epoxy profiles through iterative manufacturing trials and mechanical tension and bending experiments, complemented by fastener fixation and thermal expansion measurements, as well as life-cycle assessment. The results show that the hollow profiles reach timber-like stiffness and strength, deliver over 70% lower embodied carbon than aluminium, and can be manufactured with sufficient geometric quality for façade applications using low-budget production techniques. Although challenges remain in stiffness, fire performance and long-term durability, this project provides a strong proof of concept for future carbon reduction in façade design.