There is higher growth rate of human population and livestock population, due to this, the gap between demand and supply for feed is also increased. High price and insufficient food supply lead to malnutrition in animals. Afterward, antibiotic resistance is also a burning issue. So, there is need to search for economically cheap and organic feed for animal feeding. Therefore, unconventional feeding is best option. Unconventional animal feeds exhibit unique characteristics and considerable variability. However, their effectiveness in monogastric animals is often limited by high levels of anti-nutritional factors and poor palatability. Feed fermentation may provide a viable solution to these challenges. Additionally, fermented unconventional feeds offer significant economic benefits and can serve as an effective alternative to antibiotic growth promoters, especially in light of increasing antibiotic restrictions, showing great promise in animal nutrition. This article delves into the types and characteristics of fermented unconventional feeds, the fermentation processes involved, their application outcomes, as well as the challenges and future prospects in their use for monogastric animals. We aim for this comprehensive overview to be a valuable resource for the development and implementation of unconventional feed resources in the feed industry.