Achieving carbon neutrality in the building sector is central to Malaysia’s urban decarbonisation strategy. This study examines the implementation pathways of the Kuala Lumpur Net Zero Carbon Buildings (NZCB) Roadmap in Kuala Lumpur, focusing on regulatory compliance mechanisms, lifecycle cost implications, and data-driven retrofit prioritisation. The research develops an integrated assessment framework combining building energy benchmarking, operational carbon intensity analysis, embodied carbon accounting, and financial feasibility modelling. Compliance pathways are evaluated across new developments and existing building stock, considering alignment with national energy efficiency regulations, municipal planning guidelines, and green building certification standards. A multi-criteria retrofit prioritisation model is proposed, incorporating energy savings potential, marginal abatement cost (MAC), payback period, occupant comfort improvement, and carbon reduction per square metre. Scenario simulations compare incremental efficiency upgrades, deep energy retrofits, and renewable energy integration strategies under different carbon pricing assumptions. Results indicate that targeted retrofits in high-intensity commercial and mixed-use buildings yield the greatest emissions reductions per unit investment, while bundled measures combining efficiency and on-site solar generation optimise long-term cost performance. The study provides a structured decision-support framework for municipal authorities, property owners, and investors to accelerate NZCB adoption. By aligning compliance requirements with economic feasibility and carbon impact metrics, the proposed approach strengthens policy implementation, enhances transparency, and supports Kuala Lumpur’s transition toward a resilient, low-carbon urban built environment.