This study conducted a comprehensive and thorough evaluation of budget expenditures on agriculture in Poland from 2004 to 2022 through the prism of fiscal policy functions (i.e., allocative, redistributive, and stabilizing functions). The volume, fundamental dynamics and structure of the budget expenditures on agriculture were meticulously analyzed, as were the impacts of those expenditures on the implementation of key objectives of agricultural policy—that is, objectives related to the level and stability of farm income and the dynamics of investment in agriculture. It was determined that redistributive expenditures dominated the structure of budget expenditures on agriculture during the post-accession period. By contrast, the shares of allocative and stabilization expenditures fluctuated widely. Moreover, agricultural budget expenditures had a positive effect on reducing the income disparity of farmers relative to other socioeconomic groups. However, the redistributive effect of budget expenditures was only strong during the initial few years after Poland acceded to the European Union. The findings of this study revealed that agricultural budget expenditures have a positive effect on the stabilization of agricultural income and the investment activity of farmers, thereby supporting development processes in agriculture.