As a crucial element of urban green infrastructure, informal green spaces (IGS) provide signifi cant ecological and social advantages. However, due to ambiguous land tenure and weak stewardship, these spaces have seldom been systematically integrated into urban green-space frameworks. Using Hangzhou’s “Borrowed-Land Greening” (jiedi lühua) policy as a representative case, this study investigates variations in public perceptions of ecosystem services (ES) across diff erent levels of management intensity and evaluates the eff ectiveness of management interventions. A three-tier management gradient is established: original (unmanaged) IGS, low-control IGS, and high-control IGS, selecting six borrowed-land greening sites and three original IGS sites. Based on 11 ES perception indicators and 689 valid questionnaires, we employ cluster analysis, diversity indices, and chi-square tests to quantify the infl uence of management strategies on ES perception. The fi ndings indicate that borrowed-land greening signifi cantly enhances perceived ES, with the perception relative abundance index (RAI) increasing by 26.3%～29.0%. Moderate interventions in low-control IGS foster synergies between regulating and supporting services, whereas high-control IGS— achieved through refined maintenance and facility provision—substantially improve cultural services but entail a trade-off between ecological and cultural benefi ts. Building on these insights, we propose a graded management framework aligned withmanagement intensity and ES perception diff erentials: emphasizing low-control measures to strengthen ecological functions and implementing high-control measures to augment cultural services. We recommend low-intervention strategies in ecologically sensitive areas and high-control measures in densely populated districts to balance ecological and cultural trade-off s. The study off ers empirical evidence and theoretical guidance for the systematic integration of IGS into urban green-space systems and for tiered governance models, providing practical implications for low-cost, adaptive, and sustainable urban green development.