The City Hall Developer Investment Fund (CHDIF) is a housing finance initiative established by the Mayor of London and the UK Government to support and accelerate the delivery of new homes across London, particularly affordable housing. It was initially created with around £322–£324 million in public funding, designed to help unlock housing developments that are stalled or struggling to proceed due to financial or market challenges. 

The fund operates as an investment tool rather than a simple grant programme, meaning it provides flexible financial support such as loans, equity investment, and partnership funding to developers and housing providers. Its key role is to step in where traditional financing is insufficient, helping projects become viable by reducing upfront costs and sharing risk. This allows City Hall to take a more active and interventionist role in housing delivery, rather than relying solely on private developers. 

A major objective of the fund is to unlock stalled housing sites and accelerate construction, especially in situations where high costs, planning complexities, or economic uncertainty have delayed progress. By injecting targeted funding into these projects, the scheme helps bring land into use more quickly and increases the overall supply of homes. This is particularly important in London, where housing demand significantly exceeds supply.