The decentralization of land is crucial for effective production, welfare improvement, and social development. However, the formulation, outcome, and impact of land decentralization policies are influenced by political regimes, policy processes, geographical areas, and socio-economic settings. This study focuses on Vietnam's forest and forestland allocation program over the past 30 years to investigate its impact on poverty dynamics. Retrospective policy analysis and an extended random effect treatment model with longitudinal panel data collected from 53,568 plots in 12 provinces across Vietnam from 2008 to 2018 were used. The findings suggest that while the forestland allocation policy has a positive effect on poverty alleviation, it has minimal impact on the poorest household groups. Additionally, actual tree planting is more beneficial to the non-poor group, indicating a lack of incentivized policies for tree planting and inadequate consideration of the genuine livelihood needs and investment capacities of land recipients, especially poor households. Policy improvements are recommended to better align with the rationale, aims, and social expectations.