Water ecological products have multiple attributes, including public ecological services, resource rights, and operational use. Their value realization faces challenges such as strong publicness, complex rights relations, difficult market transformation, and insufficient benefit feedback. To explain how water ecological functions, under ecological security constraints, can form an institutionalized value realization process that supports rights allocation, financing, operation, and protection feedback, this paper adopts the perspective of government-market coordination and takes the practices of Shandong and Guangdong as comparative cases. It analyzes the relationships among rule supply, market transformation, and benefit feedback. The findings show that the Shandong pathway relies mainly on value accounting, resource integration, rights allocation, and green finance, reflecting a rule-supply-driven pattern; the Guangdong pathway, by relying on the green water economy, social capital participation, and consumption scenario cultivation, highlights a market-operation-driven logic. The two pathways indicate that value realization of water ecological products depends on government rule supply to clarify ecological boundaries and rights arrangements and to create conditions for market entry; market actors generate stable returns through capital investment and professional operation; and related returns are channeled back, through institutional arrangements, into river and lake management, ecological restoration, and public service improvement. In this way, the value transformation of water ecological products can operate on a sustained basis. This paper deepens the understanding of government-market coordination in the value realization of water ecological products and provides references for constructing differentiated value realization pathways in regions with different resource conditions and market foundations.