Kasawari Carbon Capture and Storage (CCS) project is positioned as the world largest offshore CCS upon its commencement by 2025. It is developed as the first CCS project by PETRONAS. It targets to inject up to 3.7Mt CO2e per annum (MTPA), store approximately 80MT of CO2e over 25 years of operation. The scale is significant as it represents 9% of global CCS operation (2021) and anchors PETRONAS’ pathway for Net Zero Carbon Emission (NZCE) by 2050. This paper elaborates on the key challenges, major decisions, and learnings for value assurance in scope definition throughout Framing, Feasibility, and Concept Select phase as per Front End Loading (FEL) methodology. It serves as a future reference in overcoming similar CCS scale complexity and spur momentum for larger industry adoption to meet Net Zero Emissions target by 2050.