Energy efficiency is the first means of fueling a sustainable global energy system and a cost-effective mitigation action with a negative marginal abatement cost of -132 US-Dollar per tonne of CO2 equivalent, as identified in the Cambodia’s Long-Term Strategy for Carbon Neutrality (LTS4CN). Investments in energy efficiency can have positive macroeconomic impacts, boosting economic activity and often leading to increased employment apart from bringing significant benefits to Cambodia’s economy. Major energy efficiency investment opportunities were identified in the buildings, industry, and public sectors in line with updated NDC. The report further discusses the potential financial instruments for the promotion of energy efficiency in Cambodia.