This study examines how the Swedish and Norwegian welfare models ensure sustainable welfare through their fiscal structures and social policies. The concept of the welfare state developed after World War II to protect individuals from social risks and ensure fairness in income distribution. It has been supported by comprehensive fiscal and social tools, particularly in developed countries. However, in the 21st century, developments such as globalization, digital transformation, demographic aging, environmental problems, and COVID-19 have challenged the fiscal foundations of the welfare state, and increased public spending has brought fiscal sustainability debates to the forefront. The Swedish model aims to reduce income inequality through a high tax base, comprehensive social transfers, and central coordination. Shaped by universalist policies and the "People's House" concept, the system is based on full employment, poverty prevention, and strengthening social security mechanisms. Fiscal sustainability was achieved through tax reforms, budget discipline, and market-based regulations following the financial crisis of the 1990s. Digitalization and the active role of local governments increase efficiency and fiscal discipline in service delivery, while addressing access issues for vulnerable groups. The Norwegian model, with its public-centered fiscal structure, strategic management of oil revenues, and culture of social consensus, offers a resilient welfare system against crises. The Norwegian Sovereign Wealth Fund plays a significant role in financing macroeconomic stability and social rights. Digital services and coordination of local governments increase fiscal efficiency and inclusivity, while elements of social solidarity, such as the dugnad culture, strengthen the sustainability of the system. Both models rely not only on securing social rights but also on the effective and equitable use of fiscal policy tools. Tax policies, public spending, transfer mechanisms, and natural resource funds both reduce income inequality and act as a fiscal buffer during times of crisis. The examples of Sweden and Norway demonstrate that a strong fiscal infrastructure, inclusive policies, and digital transformation are critical for the long-term sustainability of the welfare state.