The relationship between public expenditure and economic growth has been a focal point of fiscal policy analysis for over a century, largely shaped by the competing hypotheses of Wagner’s Law and Keynesian theory. This study presents a comprehensive bibliometric analysis to map the intellectual structure and research trends surrounding Wagner’s Law within the broader discourse on public expenditure and economic growth. Using a systematic search in the Scopus and Web of Science databases with the keywords “Public Expenditure,” “Economic Growth,” and “Wagner,” a total of 69 relevant documents published between 1979 and 2025 were retrieved. The merged dataset was analysed using the Biblioshiny package in R. The results reveal a modest annual growth rate of 1.52% in publications, with an average of 16.04 citations per document and a moderate international collaboration rate of 13.04%. The intellectual landscape is dominated by empirical validations of Wagner’s Law across diverse economies, employing time-series econometric techniques. The findings highlight the persistent relevance of Wagner’s Law in fiscal policy research, the growing methodological sophistication in empirical testing, and emerging thematic clusters linking public spending to sustainable and inclusive growth. This study contributes a data-driven overview of the evolution, influence, and research frontiers in Wagner’s Law scholarship.