The food system needs to be reformed to ensure food and nutritional security for everyone. One way to achieve this is by providing affordable, healthy, and nutritious diets. Millets, rich in essential nutrients like carbohydrates, proteins, dietary fiber, lipids, and phytochemicals, can play a key role in tackling food insecurity and malnutrition. However, their nutritional value and digestibility are significantly influenced by processing methods. Millets are often processed to remove inedible parts, extend shelf life, and enhance their nutritional, functional, and sensory qualities. Techniques such as fermentation, germination, parboiling, dehulling, extrusion, cooking, puffing, flaking, popping, malting, and milling can either improve or reduce their nutrient content. Understanding how these processes affect millets is crucial for the food industry, researchers, and consumers to select methods that preserve nutrients, increase bioavailability, and contribute to better food and nutrition security. Suitable processing techniques can be used to reduce the antinutrients in millets, too. This chapter examines how different processing methods impact the nutritional composition of both major and minor millets.