To solve the Multi-Objective Optimization Problem (MOOP) of a two-stage helical gearbox with double gears in the second stage, this work applies the MAIRCA approach. The objective is to determine which critical design elements are most effective in maximizing gearbox efficiency while reducing the gearbox’s bottom area. Three important design factors were chosen for this purpose: the first stage’s gear ratio and the coefficients of wheel face width for the first and second stages. Additionally, the Multi-Criteria Decision Making (MCDM) problem was handled by the MAIRCA strategy, and the weight criterion for solving the MOOP was determined using the MEREC approach. The results of the research help in the building of a two-stage helical gearbox with double gears in the second stage by identifying the most beneficial values for three major design parameters.