The petroleum refining and petrochemical sectors are cornerstone drivers of India's industrial economy, yet they concurrently represent some of the most stubborn hard-to-abate sources of greenhouse gas (GHG) emissions. As India marches toward its ambitious Nationally Determined Contributions (NDCs) target of achieving Net-Zero emissions by 2070, deep decarbonization of these downstream hydrocarbon segments is no longer optional. This comprehensive review article explores the intricate chemical landscapes, systemic operational constraints and evolving regulatory compliance structures governing the Indian refining and petrochemical landscape. Chemically, the sector relies heavily on carbon-intensive processes, including steam methane reforming (SMR) for hydrogen production, high-severity fluid catalytic cracking (FCC), and fossil-fueled steam cracking for olefins. Mitigation vectors require radical process alterations, shifting from grey to green hydrogen via water electrolysis, deploying carbon capture, utilization, and storage (CCUS) technologies, electrification of high-temperature cracking furnaces and transitioning to bio-based and plastic waste-derived circular feedstocks. However, scaling these solutions in India faces multi-dimensional constraints. These include high capital expenditures (CAPEX), nascent domestic supply chains for electrolyzers, land-use barriers for localized solar or wind integration, and an absence of a mature downstream CO2 transport network. Concurrently, statutory landscapes are shifting rapidly. Regulatory compliance frameworks, including the Bureau of Energy Efficiency's (BEE) Perform, Achieve, and Trade (PAT) scheme, the newly instituted Carbon Credit Trading Scheme (CCTS), and green hydrogen mandates, are exerting structural pressure on operators. This review synthesizes these chemical paradigms, operational roadblocks and statutory mandates into a strategic roadmap, providing a holistic baseline for engineers, policy architects and corporate strategists navigating India’s energy transition.