Defence Infrastructure Organisation (DIO) is an operating arm of the Ministry of Defence (MoD) in the United Kingdom, which is responsible for the built and rural estate.

The DIO was formed in 2011 in order to bring together the management of the MoD's estate, to reduce its running costs and create commercial opportunities.

[1] It was criticised by the National Audit Office in November 2016 because the performance regime it had set for Capita, its strategic outsourcing partner, was "not fit for purpose" and was failing to incentivise sustainable spending reductions.

[2] DIO manages around 1.8% of the UK's landmass, including 115,000 non-residential buildings and 50,000 houses.

[1] It is divided into six operating divisions, under the Corporate HQ:[3] The Ministry of Defence Guard Service also remains part of DIO.