The Modern Capital Metropolitan Area serves as a core spatial platform for advancing the coordinated development of the Beijing-Tianjin-Hebei region in greater depth in the new era. Promoting its development is an important practice for safeguarding the functions of the capital, advancing coordinated regional development, and improving the system of cross-jurisdictional spatial governance. From the perspective of endogenous metropolitan evolution, this study constructs an analytical framework, and systematically examines the formation basis, evolutionary dynamics, practical constraints, and optimization pathways of the Modern Capital Metropolitan Area. The findings show that the endogenous evolution of the Modern Capital Metropolitan Area follows the “green-smart-resilient symbiosis law” and is jointly driven by six endogenous variables: the endowments of production, living, and ecological elements; flow distance; the law of scale; technological innovation; dynamic preferences; and institutional innovation. A comparative analysis with the Shanghai Metropolitan Area, the Guangdong-Hong Kong-Macao Greater Bay Area, and the Tokyo Metropolitan Area reveals that the Modern Capital Metropolitan Area still faces a number of constraints, including insufficient coordination among production, living, and ecological endowments, relatively strong flow-distance constraints, an underdeveloped polycentric spatial structure, weak coordination along innovation chains, inadequate guidance of dynamic preferences, and lagging provision of institutional innovation. Future development should therefore improve the endogenous evolutionary mechanism by promoting complementarity among production, living, and ecological endowments, advancing spatial integration, fostering clustered agglomeration structured around “one core, two central cities, three strategic poles, and multiple nodes,” strengthening the integration of “quality-talent-innovation,” guiding dynamic preferences, and promoting institutional innovation, thereby facilitating the formation of a high-quality and coordinated development pattern driven by endogenous evolution in the Modern Capital Metropolitan Area.