China National Offshore Oil Corporation is the largest offshore oil and gas producer in China. Headquartered in Beijing, CNOOC was founded in 1982. After over 30 years of reform and development, it has become an international energy company with prominent core business, a complete industrial chain and business spreading across 40 countries and regions. The five main business segments of the Company are oil & gas exploration and development, engineering and technical services, refining and marketing, natural gas and power generation and financial services.

On November 1, 2017, CNOOC changed its Chinese registration name while transforming from an enterprise owned by the whole people into Company Limited (wholly state-owned).

The Company was ranked 64th in 2020 Fortune Global 500 and 30th in Petroleum Intelligence Weekly (PIW)'s World's Top 50 Oil Companies. At the end of 2020, Moody's and Standard & Poor's rated the Company with credit ratings of A1 and A+, and the outlook is stable.