This thesis investigates why Brazilian social commerce converts fewer than 1 (percentage) of visitors into buyers, despite the high engagement achieved on social networks. Literature review and market data reveal four structural bottlenecks: fragmented purchase journeys, lack of proprietary data, reliance on human agents, and transaction insecurity. Interviews with social-first fashion professionals confirm that each jump between Instagram, WhatsApp, and an external site increases cart abandonment and operating costs. The study proposes a Social Commerce 4.0 solution composed of conversational AI, tokenized purchase profiles, instant payments, and invisible antifraud, organized into four technological layers. The model reduces checkout from nine to three clicks, enables 24/7 service, and is expected to double the conversion rate. A three-phase roadmap (PoC, Beta, Scale) and clear KPIs, conversion, checkout time, chargeback rate, and NPS, guide implementation. The conclusion is that unifying chat, recommendation, and payment within a single environment turns social attention into revenue and creates sustainable competitive advantage for fashion brands in Brazil.