OJSC OMZ (originally known as Ural Machine-Building Plants) was formed in 1996 from the Ural Heavy Machine-Building Plant (OJSC Uralmashzavod) and the Welded Machine-Building Structures Plant (OJSC ZSMK).

Uralmashzavod was one of the first to create and re-equip core industries of the national economy, which even today still shape the Russian economy and budget. Machinery and equipment manufactured at Uralmashzavod operate in 42 countries, including in Europe, Asia, and Latin America.

In 1998, the company was joined by Izhorskiye Zavody, and was renamed to OJSC United Heavy Machinery Plants (Uralmash-Izhora Group) (OJSC OMZ). 1998
Izhorskiye Zavody is the oldest company in Russia; it laid the foundation for development of the Russian machine-building industry and was known as the Admiralty's Izhorskiye Zavody for almost two-hundred years. In the 1950s, Izhorskiye Zavody created a specialized production stream to produce excavators for the country's growing mining industry. In the 1960s, Izhorskiye Zavody created specialized metallurgical and machine-building capacities for serial production of equipment for NPP operating with water-cooled power reactors.
2003 An important stage in the company's development was when in September of 2003 it issued ordinary shares of OMZ in the form of American Depositary Receipts (ADR) on the London Stock Exchange.
In 2004, OMZ Group was joined by the Czech companies ŠKODA JS a.s., ŠKODA Hute s.r.o. and ŠKODA Kovarny s.r.o. Later, in 2007, the companies ŠKODA Hute s.r.o. and ŠKODA Kovarny s.r.o. were merged into one legal entity – Pilsen Steel s.r.o.
ŠKODA JS a.s. has been engaged in the engineering and supply of nuclear power equipment for more than fifty years. Over this period, ŠKODA JS a.s. acquired substantial experience and became a reliable supplier of NPP equipment throughout the entire world.
During the period of 2008-2011, a number of heavy machine-building companies came under the management of United Heavy Machinery Plants, including Cryogenmash, Uralmashzavod, Uralhimmash, Glazovsky Zavod Himmash, and Uralenergomontazh. 2008