Basil is most commonly used fresh, and in cooked recipes, is generally added at the last moment, as cooking destroys the flavour quickly. The fresh herb can be kept for a short time in plastic bags in the refrigerator, or for a longer period in the freezer, after being blanched quickly in boiling water. Place fresh leaves in a dry jar with a pinch of salt, and cover with olive oil. The dried herb also loses most of its flavour, and what little flavour remains tastes very different, with a weak coumarin flavour, like hay.

Mediterranean and Thai cuisines frequently use basil, the former frequently combining it with tomato. Basil is one of the main ingredients in pesto � an Italian sauce from the city of Genoa. The most commonly used Mediterranean basil cultivars are "Genovese", "Purple Ruffles", "Mammoth", "Cinnamon", "Lemon", "Globe", and "African Blue". Vietnamese and Chinese also use fresh or dried basils in soups and other foods. In Taiwan, people add fresh basil leaves to thick soups . They also eat fried chicken with deep-fried  basil leaves.

Basil is sometimes used with fresh fruit and in fruit jams and sauces � in particular with strawberries, but also raspberries or dark-colored plums. Arguably the flat-leaf basil used in Vietnamese cooking, which has a slightly different flavour, is more suitable for use with fruit.

When soaked in water the seeds of several basil varieties become gelatinous, and are used in Asian drinks and desserts such as falooda or sherbet. Such seeds are known variously as sabja, subja, takmaria, tukmaria, or falooda seeds. They are used for their medicinal properties in Ayurveda, the traditional medicinal system of India.