QinetiQ (/kɪˈnɛtɪk/ as in kinetic) is a British defence technology company headquartered in Farnborough, Hampshire. It operates primarily in the defence, security and critical national infrastructure markets and runs testing and evaluation capabilities for air, land, sea and target systems.

As a private entity, QinetiQ was created in April 2001; prior to this its assets had been part of the Defence Evaluation and Research Agency (DERA), a now-defunct British government organisation. While a large portion of DERA's assets, sites, and employees were transferred to QinetiQ, other elements were incorporated into the Defence Science and Technology Laboratory (DSTL), which remains in government ownership. Some former DERA locations have thus become key sites for QinetiQ. These include Farnborough, Hampshire; MoD Boscombe Down, Wiltshire; and Malvern, Worcestershire.

In February 2006, QinetiQ was floated on the London Stock Exchange. The privatisation process was subject to an inquiry by the UK's National Audit Office, which was critical of the generous incentive scheme available to the company's management. QinetiQ has completed numerous acquisitions of defence- and technology-related companies, primarily those that are based in the United States, and is a trusted supplier to the US government. QinetiQ USA operates under a Special Security Arrangement which allows it to work independently and separately on some of the most sensitive United States defense programs despite its foreign ownership. It has also spun off some of its technologies into new companies, such as Omni-ID Ltd. It is currently a constituent of the FTSE 250 Index.

"QinetiQ" is an invented name. "Qi" is supposed to reflect the company's energy, "net" its networking ability, and "iq" its intellectual resources. The name was adopted in early 2001 as a marker of Defence Evaluation and Research Agency (DERA) privatisation; the rebranding reportedly cost £400,000.

In early 2001, defence minister Lewis Moonie announced the creation of QinetiQ via the privatisation of the Defence Evaluation and Research Agency (DERA). At the time, Moonie stated that the entity would remain a British business, being based in the UK, and that the Ministry of Defence (MoD) would retain a 'special share' in the company, while safeguards would be in place to prevent conflicts of interest.

By April 2002, while QinetiQ had taken steps to operate on a commercial basis and saw third parties as its key growth area, 80% of its annual sales was reportedly being derived from the UK MoD. It was observed that QinetiQ's close relationship with the MoD gave it a competitive edge over most private-sector rivals.

Initially, QinetiQ was entirely owned by the British government; it was planned for a stock market flotation of the firm to be conducted sometime during 2002. However, this flotation was postponed; according to aerospace industry periodical Flight International, a lack of investor confidence was the principal reason for the delay.

In late 2002, the Carlyle Group, an American private equity firm, publicly declared its intention to purchase a large stake in QinetiQ. In February 2003, the Carlyle Group completed the acquisition of a 33.8% share for £42 million. Prior to QinetiQ's flotation years later, ownership of the firm was divided between the MoD (56%), Carlyle Group (31%) and staff (13%). The Carlyle Group was expected to remain invested in QinetiQ for between three and five years, after which a stock exchange float would take place.