A robust immune system is essential for maintaining good health. The characteristics of a robust immune system is to safeguard the body against invasion of outer microscopic materials and subsequent infection. Food ingredients have long been acknowledged to play a crucial role in the growth and development of the human body, providing protective functions against foreign matter that can pose serious public health issues. According to numerous studies, natural products are rich in bioactive substances like vitamins such as vitamins A, C, and E, minerals, and phytochemicals such as beta-carotene, flavonoids, tannins, and phenolics. These substances can improve our immune system by promoting lymphocyte proliferation, scavenging free radicals, lowering oxidative stress, enhancing anti-inflammatory and immunomodulatory pathways, and promoting platelet aggregation. Through encapsulations, bioactive substances can safely deliver inside the body. The advantages of encapsulated bioactives include their high bioavailability and stability, prolonged release of functional compounds, capacity to prevent undesirable interactions, and excellent antibacterial and antioxidant activity. In summary, this chapter will present an in-depth review of the human immune system and the immune-boosting potential of food bioactives, emphasising their potential mechanism and the techniques employed for applications in food matrices.