Lean manufacturing focuses on eliminating waste across production. In supplier selection, applying lean principles helps identify partners that minimise waste in the supply chain. This study proposes an integrated multi-criteria decision-making (MCDM) approach for supplier selection in Vietnam's garment industry. It combines stepwise weight assessment ratio analysis (SWARA) with a regret theory-based evaluation based on distance from average solution (EDAS) under spherical fuzzy conditions. The SF SWARA method determines evaluation criteria weights, while the regret-based SF EDAS ranks suppliers by proximity to the ideal solution. Findings show the hybrid approach enhances accuracy and reliability in lean supplier selection, supporting cost reduction and quality improvement. The study also offers a roadmap for practitioners and policymakers to optimise supplier evaluation, strengthen supply chain performance, and advance sustainable lean practices. Overall, it enriches decision-making methodologies within lean supply chain management and extends relevance to other industries facing similar challenges.