Petroliam Nasional Berhad, commonly known as PETRONAS (stylised in all caps), is a Malaysian multinational oil and gas company headquartered in Kuala Lumpur. Established in 1974, it is a legal entity incorporated under the Malaysian Companies Act 1965 and reports to the company's Board of Directors. Petronas is vested with all oil and gas resources in Malaysia and is entrusted with the responsibility of developing and adding value to these resources.

Petronas is a vertically integrated company and actively in all areas of the oil and gas industry, including exploration and extraction, refining, distribution and marketing, power generation, and trading. Petronas has operations in over 100 countries and has sales office in 22 countries, produced around 9 billion barrels of oil equivalent and 50 trillion cubic feet of gas and has around 1,000 service stations nationwide as well as 1,200 Engen stations in South Africa and Sub-Saharan Africa. As of 31 December 2024, Petronas had total proved reserves of 24.5 million barrels (3,900,000 m³) of oil equivalent per day.

The company also has a strong presence in the lubricants market through its wholly owned subsidiary Petronas Lubricants International, which operated in over 100 markets internationally. Petronas Carigali, its principal subsidiary and one of its largest businesses, responsible for hydrocarbon exploration and production. Other subsidiaries include Petronas Dagangan, for gas trading and marketing, and Petronas Chemicals for petrochemical as well as Gentari for clean energy use and commercialization. It also offers higher education through its university, the Universiti Teknologi Petronas (UTP). The Malaysia Petroleum Management (MPM), its key division and a governing body for the petroleum resources development since Petronas' establishment, oversaws the entire lifecycle of the country's upstream oil and gas assets.

In the annual Fortune Global 500 list for 2022, Petronas was ranked at 216th. It also ranked 48th globally in the 2020 Bentley Infrastructure 500. The Financial Times has identified Petronas as one of the "new seven sisters", considered to be influential and mainly state-owned national oil and gas companies from countries outside the Organisation for Economic Co-operation and Development (OECD). Petronas provides a substantial source of income for the Malaysian government, accounting for more than 15% of the government's revenue from 2015 to 2020.

A total of 0.69 percent of the gases released through global industrial processes from 1988 to 2015 came from the company's activities. Therefore, Petronas is a major contributor to climate change, a phenomenon that poses many risks to health, jobs, food and water supply stability, security, and economic development. The company celebrates its 50th anniversary in 2024.

Before the formation of Malaysia, Royal Dutch Shell (now Shell plc) first began the oil exploration in Miri, Sarawak after Charles Brooke signed the first Oil Mining Lease in 1909. In 1910, the first oil well was drilled in Miri. This oil well is later known as the Grand Old Lady. In 1929, oil was discovered in Brunei. There were no other drilling activities in Borneo or British Malaya until 1950s. Shell was still the only oil company in the area in 1963, when the Federation of Malaya, having achieved independence from Britain six years earlier, united with Sarawak and Sabah, both on the island of Borneo, to become Malaysia. Authorities in both new states maintained a close relationship with Shell, which brought Malaysia's first offshore oilfield to fruition in 1968.

In 1966, the enactment of Petroleum Mining Act gave Exxon and Shell rights to explore oil territories and produce oil royalties and tax payments to the government. In the late 1960s, Esso and Continental Oil were given concessions to explore oil off the shores of the east coast of Peninsular Malaysia. By 1974, Malaysia's output of crude oil stood at about 90,000 barrels per day (14,000 m³/d) to 99,000 barrels per day (15,700 m³/d).

Several factors converged in the early 1970s to prompt the Malaysian government into setting up a state-owned oil and gas company. In 1972, the oil price per barrel was US$1.50, which later rose to US$2.28 per barrel. War in the Middle East and an oil embargo by the Organization of Petroleum Exporting Countries (OPEC) caused the price per barrel to rise to US$12.00, which further incentivised Malaysia to set up its own oil company. Several countries such as United Arab Emirates, Egypt and Indonesia have adopted the production sharing agreement instead of a concession system for oil revenue distribution. The Malaysian government also believed that foreign oil companies did not properly inform the government regarding the oil exploration activities in their own concessions (such as the new discovery of oil fields), thus resulted in a loss of revenue to the government. The formulation of Malaysian New Economic Policy in the early 1970s encourages Malaysians to take control of various modern industries and to open more economic opportunities for the bumiputeras.