Gross Domestic Product (GDP) has long served as the primary indicator of economic performance, yet it provides a narrow view of prosperity. While GDP measures aggregate output, it overlooks income inequality, environmental degradation, and the broader value created by innovation and human capital. In an era defined by climate change, rapid technological transformation, and widening social disparities, reliance on traditional GDP is increasingly insufficient. The emerging concept of “Keynesian 2.0” seeks to modernize macroeconomic thinking by integrating sustainability, equity, and innovation into both measurement and policy design. This framework reinterprets Keynesian demand management by aligning fiscal stimulus with long-term structural goals. It advocates incorporating environmental costs through Green GDP, recognizing human and natural capital via Inclusive Wealth metrics, and promoting mission-oriented public investment to guide technological change. By embedding innovation and social inclusion directly into economic evaluation, Keynesian 2.0 moves beyond short-term output growth toward resilient and equitable development. Ultimately, it proposes a redefined GDP that better reflects real societal progress and supports sustainable prosperity for future generations.