The growing digitalisation of public administration and the increasing number of countries affected by armed conflicts raise important questions about the role of e-government in sustaining government revenue mobilisation under institutional stress. This study examines how the development of digital government influences different sources of public revenue and whether armed conflict moderates this relationship across countries. The analysis uses cross-country panel data for 2003–2024, combining indicators of e-government development from the UN EGDI database, fiscal indicators from the World Bank Open Data, and conflict information from the UCDP/PRIO Armed Conflict Dataset, estimated using two-way fixed effects models with robust clustered standard errors. The results show that economic development is the strongest determinant of revenue mobilisation, with GDP per capita coefficients ranging from 0.95 to 1.22 across models. The overall EGDI does not demonstrate a statistically significant direct effect on tax revenue or revenue excluding grants, although weak interaction effects suggest that armed conflict may reduce the fiscal effectiveness of digital governance (−0.238; p ≈ 0.10). A significant negative relationship is observed for the telecommunications infrastructure component with tax revenue (−0.362; p = 0.005) and revenue excluding grants (−0.349; p = 0.011). For customs duties and social contributions, the results indicate no systematic relationship between e-government development and revenue performance, highlighting the dominant role of macroeconomic conditions in shaping fiscal capacity.