This article critically examines the effectiveness of the Competition Commission of India’s (CCI) enforcement in digital markets between 2015 and 2025, a period marked by the emergence of multi-sided platforms, data-driven market power, network effects, and rapid technological change that have amplified risks of gatekeeper dominance and consumer exploitation. The study assesses whether ex-post, complaint-driven antitrust enforcement has delivered deterrence, compliance, market impact, proportionate penalties, effective remedies, and timely outcomes in India’s digital economy. Using a mixed-methods design combining doctrinal analysis of CCI orders with empirical assessment of enforcement outcomes, review of appellate proceedings, and structured comparative institutional analysis of the European Commission, US FTC/DOJ, and UK CMA, the evidence base synthesises 162 papers on CCI effectiveness and India’s digital competition framework. Across approximately 30-40 platform investigations between 2015-2025, 40-50 per cent of concluded matters resulted in infringement findings, with total penalties of approximately INR 2,487 crore based on the major cases analysed in this study, driven by landmark actions against Google (Android: INR 1,337.76 crore; Play Billing: INR 936.44 crore) and Meta (WhatsApp: INR 213.14 crore). While the aggregate across all platform investigations during this period may be higher, a comprehensive publicly verifiable breakdown is not available. Despite analytical sophistication and detailed behavioural remedies, major findings indicate limited deterrence, delayed compliance, and minimal market-structure change, with persistent dominance (Google >95 per cent in search and Android app stores; WhatsApp >80 per cent in messaging). Procedural inefficiency is central: investigations typically take 3-5 years, and, with appellate stays, enforcement extends to 7-10 years, undermining remedy implementation. The article concludes that traditional ex-post enforcement alone is insufficient for systemic digital market power, supporting a hybrid ex-ante/ex-post framework including obligations for systemically significant digital enterprises, alongside reforms on interim measures, penalty calibration based on global turnover, technical monitoring capacity, and international cooperation.