This is a list of the biggest oil companies in the world. here is a list of the largest oil companies in the world. It is surprising to know that the British Petroleum is the fourth-largest oil company in the world by annual revenue and there are other major oil companies that rule the oil industry. This list of the top petroleum companies on Earth is ranked according to Forbes, the business magazine and resource that regularly runs down the top 10 major oil companies.What are the world's largest oil companies? Take a look at this list and you'll find out which oil companies are the biggest and most powerful. Same names may surprise you, others may not, but either way, the largest oil companies in the world are presented here. So the next time there's a catastrophic oil spill, the name of the global petroleum company behind it won't come as a surprise.