<p>Steel–concrete composite (SCC) girders are widely used in modern infrastructure because of the efficient utilization of the constituent materials, but designing them can be complicated and costly due to many interacting factors. Unlike RC girder and steel girder designs, the design of the SCC girder involves more variables, and merely satisfying the design criteria as prescribed by the national standards may not provide optimum girder proportions for a given set of loading. Therefore, this research aims to address these issues by developing an optimization framework for SCC girders using a genetic algorithm (GA)-based approach. The study integrates the design guidelines of the Indian standard IRC: 22 to ensure compliance with serviceability and collapse limit state requirements. A GA is employed to efficiently explore the design space, identifying optimal solutions for SCC girders while enhancing the effectiveness of the design process. Subsequently, a parametric study is conducted to generate optimum design trends by analyzing critical parameters such as span length, degree of shear connection, steel girder grade, and concrete grade. The findings of the study provide insights into cost variations and key design variables, providing structural engineers a useful information for achieving efficient and economical designs. The design trends demonstrate the influence of varying parameters on both structural performance and cost-effectiveness. This knowledge is crucial for informed decision-making during the design phase, contributing to more efficient and cost-effective structural solutions. Additionally, a concise review of current optimization practices for SCC beams contextualizes the study’s contributions and highlights its relevance to the field.</p>