The Goods and Services Tax implementation in India on July 1, 2017, represented a paradigm shift in the nation’s fiscal policy, aiming to dismantle internal trade barriers and unify the indirect tax structure. This research paper evaluates the impact of GST on the competitive advantage of Patanjali Ayurved Limited, a home-grown FMCG giant that disrupted the Indian market with its “Swadeshi” (indigenous) and Ayurvedic value proposition. While Patanjali enjoyed a 100% growth rate in FY2016-17, reaching ₹100 billion in revenue, the post-GST era saw a significant stagnation, with sales changing only marginally by March 2018. Through an analysis of supply chain dynamics, pricing strategies, and tax pass-through effects, this study explores how the formalization of the economy under GST leveled the playing field for multinational corporations and challenged Patanjali’s cost-leadership model. The findings indicate that while GST provided structural benefits in logistics and tax rationalization, the increased compliance burden and the removal of regional tax exemptions previously leveraged by Patanjali temporarily eroded its competitive edge.