Hochtief AG is a global provider of infrastructure technology and construction services, with locations in North America, Australia, and Europe. The Essen based company is primarily active in the fields of high tech, energy transition, and sustainable infrastructure. With the international projects making up 95% of the company's revenue, Hochtief was among the largest international construction firms in 2023.

In Australia, the group is active through its subsidiary Cimic (100% since 2022). Via its wholly owned subsidiary Turner, Hochtief is a leader in commercial construction in the United States. Since June 2018, Hochtief has held a 20% stake in Abertis. Abertis directly owns 99.1% of the toll road operator Abertis Infraestructuras.

Since ACS Group first acquired shares in Hochtief in 2005, it has increased its shareholding to 75.71% in 2023.

In 1873, brothers Philipp Helfmann (a bricklayer) and Balthasar Helfmann (a locksmith), originally from Kelsterbach, founded the company Gebrüder Helfmann in Frankfurt am Main. While Balthasar was responsible for the completion of construction contracts, Philipp developed the financing side of the business. Their first major contract was for the University of Giessen in 1878. By the 1880s, the company had begun to produce its own construction materials but was still only a regional player. Shortly after the death of Balthasar, Philipp Helfmann transformed the company into a joint-stock corporation for building construction and civil engineering named Aktiengesellschaft für Hoch- und Tiefbauten (Construction and Civil Engineering Corporation) in 1896, just before the German Stock Exchange Act came into force.

A major development was the contract for the spa in Bad Orb in 1899, where the order included not just construction of the buildings, but also provision of infrastructure like roads and gardens, arrangement of finances for the project, and maintenance of some responsibilities for operation after the construction. Also in 1899, another turnkey project, a new grain silo in Genoa, Italy, was both the firm's first international venture and its first project using reinforced concrete. Philipp Helfmann died in the same year, with his son-in-law, Hans Weidmann, taking over as Chief Executive.

The firm grew rapidly, but was not comparable with the major German construction companies of the era. In 1921, it attracted investment from the industrialist Hugo Stinnes (described by Time as the "New Emperor of Germany" for his wealth and influence) and in 1922, the firm moved its base to Essen as part of its integration into the Stinnes group. Stinnes planned to use Hochtief for all his construction projects, while Hochtief saw an opportunity to profit from the Treaty of Versailles, organising the delivery of construction materials to France as part of German reparations for World War I. Stinnes died in 1924, and within a year his industrial empire collapsed. With the help of several banks, the company (now known as Hochtief Aktiengesellschaft für Hoch- und Tiefbauten vorm. Gebrüder Helfmann) avoided insolvency. In the aftermath of the Stinnes collapse, the major utility RWE and electrical equipment producer AEG became major shareholders in Hochtief, and Hans Weidmann stepped down in 1927.

A series of major construction projects ensued, including the Echelsbach Bridge (then Germany's largest single span reinforced concrete bridge), the Schluchsee dam and work on the Zollverein colliery.

From 1933 onwards, the structures of the Third Reich influenced Hochtief's business activities. Jewish members of the supervisory board were expelled under the Nuremberg Laws in 1935. In 1937, CEO Eugen Vögler joined the Nazi Party (NSDAP) and served as leader of the Construction Industry Group as well as an honorary squad leader of the Hitler Youth. The construction business flourished under the four year plan, with its vast public works programme, including the Autobahn network, and the industrial build-up in preparation for war, for example the construction of a new truck factory for Opel in Brandenberg. Hochtief also worked on a new centre for Nazi rallies in Nuremberg. In 1936, it moved its Essen headquarters from the Pferdemarkt to its current location on Rellinghauser Straße. As war became imminent, the company began work on the Westwall defensive network. During World War II, it worked on the Atlantic Wall defences, and a range of infrastructure projects across German-dominated Europe. Hochtief also constructed buildings for Hitler himself, notably his Bavarian Alpine retreat, the Berghof, his Wolf's Lair headquarters in Rastenburg, and the Führerbunker in Berlin, where Hitler ultimately committed suicide.