Interest in the Caspian Sea first began in 1992 when an exploration program was announced by the Kazakh government. They sought the interest of over 30 companies to partake in the exploration. In 1993 the Kazakhstancaspiishelf was formed which consisted of Eni, BG Group, BP/Statoil, Mobil, Royal Dutch Shell and Total S.A., along with the Kazakh government. This consortium lasted 4 years until 1997, when seismic exploration of the Caspian Sea was undertaken.
Upon completion of an initial 2D seismic survey in 1997, the company became Offshore Kazakhstan International Operating Company (OKIOC). In 1998 Phillips Petroleum Company and Inpex joined the consortium. Kashagan was discovered in 2000.
The consortium changed when it was decided that one company was to operate the field instead of joint operatorship as had been agreed before. Eni was named the exclusive operator in 2001. In 2001 BP/Statoil sold their stake in the project to the remaining partners. With Eni as the operator, the project was renamed Agip Kazakhstan North Caspian Operating Company NV (Agip KCO).
In 2003, BG Group attempted to sell their stake in the project to two Chinese companies, CNOOC and Sinopec. However, the deal did not go through due to the partners' exercise of their pre-emptive privileges. Eventually, in 2004 the Kazakh government bought half of BG's stake in the contract, with the other half shared out among other five Western partners in the consortium that had exercised their pre-emptive rights. The sale was worth approximately $1.2 billion. The Kazakh stake was transferred to the state-owned oil company KazMunayGas. On 27 September 2007, the parliament of Kazakhstan approved a law enabling the government to alter or cancel contracts with foreign oil companies if their actions were threatening national interests.
With President Nursultan Nazarbayev appointing Maksat Idenov  to lead negotiations, KazMunayGas further increased its stake in January 2008, after its six partners and the Kazakh government agreed on compensation for the probable five-year delay that was taken in developing the field. Eni operated this project under the JV company name of AgipKCO (Agip Kazakhstan North Caspian Operating Company N.V.). Following the agreements reached on 31 October 2008 between Kazakh authorities and co-ventures under the North Caspian PSA (NCPSA), operatorship of the NCPSA was formally transferred from AGIP KCO to a new company, North Caspian Operating Company (NCOC), on 23 January 2009.
In October 2008, Agip KCO handed a $31 million letter of intent for FEED work on phase two to a joint venture of Aker Solutions, WorleyParsons and CB&I. WorleyParsons and Aker Solutions are also engaged in phase one, carrying out engineering services, fabrication and hook-up.
In November 2012, ONGC Videsh agreed to buy ConocoPhillips's 8.4% stake. The Kazakh government, however, decided in July 2013 to use its pre-emptive right to buy ConocoPhillips's stake, which it sold to CNPC later that year. The deal was already approved by Eni.
On 11 September 2013, Kashagan began oil production after years of delay, with ExxonMobil and ConocoPhillips planning to increase production over the next several years. The Oil and Gas Minister of Kazakhstan has estimated the oil field will pump 8 million tonnes of oil in 2014.