It designs, develops and manufactures a wide variety of aerospace and military systems, devices and equipment but also operates in the cybersecurity and formerly civil ground transportation sectors.

In 1968 Thomson-Brandt (a renamed CFTH) merged its electronics arm with that of Compagnie générale de la télégraphie sans fil (CSF) to form Thomson-CSF, which changed its name to Thales in December 2000.

The new company would now market Samsung Electronics' defense communication equipment, satellite communication systems and terminals, fire control systems, radar guidance equipment including detection and tracking devices, and gunner's sights; and would begin overseas exports through Thomson's sales network.

[12][13] Samsung stated that the two parent companies also intended to combine their respective areas of competitive advantage to jointly develop and sell next-generation products.

[14] In June 2001, Thales formed ThalesRaytheonSystems, an equal-ownership joint venture with Raytheon combining their radar and communication systems divisions.

[16][17] In 2006, Thales acquired Australian Defence Industries, a major manufacturer of military equipment such as smokeless gunpowder and the Bushmaster IMV.

[18] The deal would also include the Systems Integration activities (those not dedicated to telecoms operators, and covering mainly the transport and energy sectors).

[29] Thales Group supplies electronic devices and equipment used by the French Armed Forces from its past as Thomson-CSF, including the SPECTRA helmet for the army and the gendarmerie.

Thales often worked with DCNS and designed the electronics used on French ships, and it is involved in the construction of both the Horizon and FREMM programs.

In February 2004, Thales was awarded a contract for a new command and control system for the French Navy, the SIC 21, that will be fitted on the Charles de Gaulle, many vessels and shore locations.

Additionally, the initially planned French aircraft carrier PA2 involved Thales as the main designer of the ship.

Among the EU-supported projects Thales participates in are: The company's design won the competition for the Royal Navy Future Carrier (CVF).

In 2022, during the Russian invasion of Ukraine, major arms manufacturers, including Thales,[33] reported a sharp increase in interim sales and profits.

[39] In India, Thales was selected in December 2014 by the New Delhi Metro Rail Corporation (DMRC) to deliver a completely automatic fare collection system, as well as ticketing equipment.

[43] In Vietnam, the company was awarded a €265 million contract in 2017 to deliver the telecommunications system for the currently constructed Line 3 of the Hanoi metro.

In November 2016, Thales announced its intention to divest from its transport ticketing, revenue collection, road toll and car park management business.

[67] On 30 May 2005 Schabir Shaik, the financial advisor to Jacob Zuma, the deputy president of the African National Congress party, was found guilty by the High Court in Durban of organising a bribe on behalf of Thomson-CSF.

[69][70] Zuma is said to have allowed these illegal Thales arms dealings when he was the nation's deputy president and is also believed to have partaken in them as well.

The operation is the result of two investigations; the first, opened at the end of 2016, focuses on suspected corruption of a foreign official, criminal association and money laundering involving the sale of submarines, and the construction of the naval base in Brazil.

[72] In October of 2021, the Indonesian government carried out bombing attacks against civilians in Kiwirok, Bintang Mountains Regency, West Papua.

[73][74] Despite an EU arms embargo after the invasion of Crimea, Thales continued to supply systems to the Russian Army.