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 63rd in 2019 Fortune Global 500 and 31st in Petroleum Intelligence Weekly (PIW)'s 2019 World's Top 50 Oil Companies. The CNOOC brand was ranked 17th on the global oil and gas brand value list and 8th on the value-added brand list. By the end of 2019, Moody's and Standard & Poor's rated the Company with credit ratings of A1 and A+.respectively, and the outlook was stable.