As the primary institutional vehicle for patient capital in the Chinese context, government investment funds have yet to receive systematic theoretical explanation regarding their mechanisms for cultivating local innovation ecosystems. This paper operationalizes patient capital as a continuous analytical variable comprising four dimensions—time tolerance, risk co-bearing, goal multiplexity, and relational governance—and constructs an integrative analytical framework of “patient capital supply-innovation ecosystem cultivation” grounded in the structural characteristics of innovation ecosystems. The study finds that patient capital cultivates innovation ecosystems through three interconnected effects: actor activation, resource linkage, and expectation stabilization. These three effects exhibit sequential interdependence rather than simple superposition: actor activation serves as the structural prerequisite for resource linkage, while resource linkage constitutes the ecological foundation for expectation stabilization. Drawing on case analysis of Zhejiang Province’s “4+1” special fund cluster and Hangzhou’s “3+N” industrial fund cluster, the paper further finds that the key institutional condition determining whether the three effects can be effectively realized is the degree of institutional anchoring of patient capital attributes, rather than the expressed strength of policy commitments. When institutional anchoring is insufficient, fund managers will systematically deviate from a patient capital orientation under short-term performance pressures, even when patient capital is nominally pledged at the policy level. This paper bridges the theoretical dialogue between patient capital theory and innovation ecosystem theory, endogenizes capital supply structure as a key variable in innovation ecosystem evolution, and provides mechanism-level theoretical grounding for the institutional reform of current government investment fund policies.