Cottonseed oil is a cooking oil extracted from the seeds of cotton plant of various species, mainly Gossypium hirsutum and Gossypium herbaceum. Cotton grown for oil extraction is one of the big four genetically modified crops grown around the world, next to soy, corn, and rapeseed (canola), mostly Monsanto products.

The cottonseed has a similar structure to other oilseeds such as sunflower seed, having an oil bearing kernel surrounded by a hard outer hull; in processing, the oil is extracted from the kernel. Cottonseed oil is used for salad oil, mayonnaise, salad dressing, and similar products because of its flavor stability. The cottonseed oil undergoes intensive treatment after extraction to reduce the level of gossypol found in untreated cottonseed oil, the consumption of which may produce undesirable side-effects.