Trees As Infrastructure (TreesAI) is establishing nature as a critical part of urban infrastructure, alongside bridges, roads and rail, enabling investment, profitability and sustainability. Urban forests regulate a number of ecosystem processes (e.g. water and air quality) and provide tangible and intangible benefits vital for living environments. Trees produce goods such as food and timber; and are deeply connected to our societies and cultures functioning as powerful symbols. TreesAI accounts and values a number of tangible benefits—relating to carbon, water, health, energy, biodiversity and the economy—while acknowledging social and cultural co-benefits.