Transport decarbonization is essential for reducing global greenhouse gas emissions, particularly in Asia. This pilot study analyzes land transport decarbonization and net-zero strategies in Cambodia, Laos, Myanmar, Thailand, and Vietnam. It employs a novel analytical framework combining the Theory of Change model and quantitative text mining approaches to complementarily address key provisions, approaches, challenges, and implications for policymakers. The key findings are classified into content analysis of the policy documents, socio-economic and financial factors, and environmental impact. On the socio-economic front, the political stability and development stages of countries critically affect the strategic options. For instance, Thailand’s high economic status enables Intelligent Transport Systems implementation, and Vietnam’s rapid urbanization drives urban transit infrastructure investment. From a financial perspective, the availability of project funds seriously affects the choice set of investments. Chinese investments are evident in Laos, which leads to extensive investments in rail, while Cambodia depends heavily on ODA, leading to donor-driven development and institutional weaknesses. Vietnam’s shift towards market-oriented solutions in land transport development necessitates innovative financial schemes as it reduces ODA reliance. Funding sources also affect environmental consequences, as Chinese investments prioritize speedy economic development, while international organizations’ investments focus more on social equity and environmental issues. On the environmental agenda, Myanmar’s green transport projects seem driven by international pressure, most probably due to its high ODA dependence, rather than domestic policy priorities. Additionally, all five Mekong countries converge towards electric vehicles (EVs) adoption, prioritizing fuel efficiency and low-carbon emissions as well as investment in public infrastructure such as roads and buses. Policymakers in the Mekong region face complex challenges in balancing economic growth with sustainable land transportation goals, necessitating comprehensive strategies that address technological limitations, infrastructure needs, and environmental concerns.