Construction of the Pohang plant began on April 1, 1970, and was dedicated on July 3, 1973, with an initial annual capacity of 1.03 million metric tons.

"[12] POSCO first began to sell plate products in 1972 and focused its sales policies on the domestic market to improve steel self-sufficiency at home.

It made special efforts to supply quality iron and steel to related domestic companies at below export price to strengthen their international competitiveness.

[citation needed] POSCO continued to expand productivity and size at a time when the steel industries of the United States and Japan were declining.

A third-phase mill completed in 1992 further increased crude steel production to a total output of approximately 17.2 million tons a year.

However, the administration led by Kim Young Sam changed the initial policy direction of privatization of POSCO and decided not to sell government-owned stock to keep it as a government investment enterprise.

As part of the privatization process, new Chairman Lee Ku-Taek began efforts to introduce a professional management and governance system of global standards for POSCO.

[citation needed] Net earnings from POSCO's array of steel products – used in everything from screws to skyscrapers – shot up 80% to $1.66 billion in 2004 from the previous year.

In June 2022, POSCO is temporarily cutting production lines in Pohang plants as thousands of truckers go on a strike for higher pay, causing disrupted cargo transport in the country.

[19] POSCO has maintained its presence in Russia through its local subsidiary, even as the country faces widespread condemnation and international sanctions for its invasion of Ukraine.

While numerous companies have withdrawn from the Russian market in response to the ongoing war, POSCO's decision to continue operations has sparked significant criticism.

Observers argue that its actions contradict global efforts to isolate Russia economically and may be seen as enabling a regime responsible for atrocities and the loss of innocent lives in Ukraine.

If the project goes ahead, it will be the single largest foreign direct investment in India as well as being the world's biggest greenfield steel plant ever.

[citation needed] However, from 2005 till date (as of August 7, 2010), the India project has not been able to proceed due to strong opposition from the local residents in the area proposed to be given for the steel plant.

[23] There have also been claims that the project will only benefit the company while displacing more people than it employs, damaging the environment and taking India's mineral resources at a very low price.

Despite the committee's report indicating that provisions of the Forest Rights Act had been violated, the MoEF issued final order on January 31, 2011, and gave environment clearance to POSCO.

[28] The Central Government of India came out confident on 15 January 2014 that with the renewal of environment clearance, South Korean steel giant POSCO's project in Odisha would take off soon.

On July 17, 2015, news reported that South Korean steelmaker POSCO may halt a $12 billion US dollar plan agreed with Odisha, India a decade ago due to the delay in regulatory approvals.

On 13 January 2022, the Adani Group announced that it had signed an MoU with POSCO to explore the setting up of an Integrated Steel Mill in Mundra, Gujarat, with an estimated total investment of US$5 billion.

[citation needed] POSCO plans to build the US$1 billion plant in two phases for hot-rolled by the end of 2012 and cold rolled products by the time of December 2009.

Posco also plans to build a $250 million plant in the city of Altamira, Mexico, to produce 400,000 tons of galvanized steel sheet a year for automakers.

On June 30, 2006, POSCO completed the construction of its sixth continuous galvanizing line (CGL) at its Gwangyang mill in the South Jeolla Province.

[34] In February 2013 POSCO signed a Memorandum of Understanding with Afferro Mining, Inc, with a view to developing iron ore resources in Cameroon.