This paper delves into the effects of public investment on primary school enrollment in low- and middle-income countries (LMICs) across three decades, from 1990 to 2020. Autoregressive distributed lag models are employed to evaluate their long-term relationship for the whole sample and four distinct sub-samples while also probing the potential non-linear nature of the relationship. Results reveal that public expenditure has a significant, positive impact on enrollment across LMICs, including low-income (LICs), lower-middle-income (LMCs), and sub-Saharan African (SSA) countries in the long run. These effects persist under non-linear model specifications. The study provides fresh empirical insights by adopting a long-term viewpoint on the nexus between educational funding and enrollment trends in LMICs. The findings highlight the critical role of sustained and efficient funding in achieving enrollment goals, a cornerstone for advancing sustainable development. Beyond conventional revenues and expenditures in the education finance literature, the study also discusses alternative policy approaches that can enhance the efficient use of allocated resources.