Many developed high density cities around the world are facing unprecedented challenges as their infrastructure facilities are aging while citizen demands are ever surging. The concerted efforts of different infrastructure stakeholders are indispensable to elevate the quality, reliability, and capacity of infrastructure systems to make high-density cities more sustainable and resilient against increasing climate change and manmade threats. To address these challenges, this paper proposes an integrated framework for multisector infrastructure asset management. For deriving the framework, case studies are conducted first on the best infrastructure asset management (IAM) practices of different countries in such diverse aspects as core process integration, contingency management, climate change response and adaptation, program coordination and orchestration, social value creation and sharing, risk management, resilience and sustainability. By using the criteria and a list of questions obtained from the case studies, interviews with different stakeholders in selected infrastructure sectors in Hong Kong are subsequently carried out to identify the barriers and possible solutions to enhancing the integrated management of multisector infrastructure assets in high-density cities. To facilitate such municipalities in managing their infrastructure assets effectively and efficiently, the proposed multisector integrated IAM framework is established from the holistic perspectives of information integration, process integration, collective decision, and harmonization between interdependent infrastructure systems.