Traditional animal feed does not fulfill the specifications of balanced food necessary for livestock which are ultimately crucial for their proper growth and productivity performance. These additives, derived from various fungal species enhance digestibility, complex feed breakdown, nutrient absorption and improve growth rate in livestock. Fungal enzymes, such as cellulase, amylase, and protease, are known to break down complex constituents of animal feed. Additionally, conventional feed does not provide the benefits of probiotics and prebiotics which is very essential for maintaining the healthy gut microbiome of the animal. Therefore, there is an urgent need to scrutinize the supplements that not only provide essential nourishment to the host but also encourage optimal growth, and development along with the improvement of the productivity of the livestock. Furthermore, fungal feed additives are gaining momentum in animal nutrition because of their astounding ability to amplify growth and boost health as they act as substitutes for antibiotics, acting as a sustainable source to combat antibiotic resistance in animals. Cell walls, polysaccharides, ergosterol, adenosine, and triterpenes of fungi feed additives are known to provide antimicrobial, antiphlogistic, anti-fatigue, antioxidant, and immunity-boosting effects. The present chapter explains the comprehensive discussion on feed additives, their classification, and role along with the effect of supplementing fungal feed additives in livestock diets.