Small island protected areas face compounding pressures from rapid urbanization, constrained land use, biodiversity loss, and intensifying climate and disaster risk, yet scholarship on how to finance and mainstream Nature-based Solutions (NbS) in governance-complex, nationally protected island systems remains limited. This study addresses that gap by examining the integration of NbS into climate and disaster risk management and development planning for the Siargao Island Protected Landscape and Seascape (SIPLAS), Philippines. The study combines five key informant interviews (KIIs) with local actors representing government, civil society, business, and protected area management with a systematic review of twelve national and international policy frameworks and technical toolkits. Results show that NbS initiatives in SIPLAS remain concentrated in four areas:mangrove restoration, coral reef conservation, sustainable tourism as an enabling condition, and community-based conservation, while ecosystem service valuation, blue carbon mechanisms, and standardized monitoring remain underdeveloped. Interview and documentary evidence indicate that the main barriers to scaling NbS are fragmented governance across local government units (LGUs) and the Protected Area Management Board (PAMB), limited and projectized financing pipelines, and the absence of robust metrics to demonstrate ecological and socio-economic returns. The post-Odette USAID SIBOL rapid biodiversity assessment in SIPLAS recorded325 species of flora and fauna and identified revegetation, stronger environmental enforcement, and landscape-scale restoration planning as priority actions, reinforcing the island\'s strong ecological basis for NbS expansion. Globally, finance for nature-based solutions reached about US$200 billion in 2022, but this representedonly around one-third of the level needed by 2030, highlighting the structural financing gap confronting local NbS implementation. Thepaper proposes a four-pronged mainstreaming strategy: policy integration, cross-sectoral collaboration, phased and diversified financing, and robust monitoring and evaluation. The resulting framework offers a replicable model for governance-complex small island communities seeking to translate global NbS commitments into locally actionable and financially sustainable programs.