In recent decades, swine nutritionists have become increasingly concerned about the competition between human and livestock populations for limited animal and plant resources. Consequently, research efforts have shifted towards exploring alternative, cost-effective feedstuffs and evaluating their potential for incorporation into swine diets. In addition to investigating alternative ingredients such as barley, triticale, rye, pulses, and non-conventional oilseeds and their byproduct, advancements are also being made to improve the digestibility of conventional maize and soybean meal-based swine diets, which have long been the industry benchmark for energy and protein supply. However, monogastric animals like pigs lack or have insufficient levels of enzymes necessary to break down non-starch polysaccharides and other anti-nutritional factors present in cereals and oilseed coproducts, as well as in traditional feed ingredients. Therefore, the inclusion of enzymes into pig diets is essential to maximise nutrient utilisation from a complex feed matrix. Enzymes commonly employed in the feed industry include cellulase, β-mannanase, β-glucanases, xylanases, phytases, proteases, lipases, and galactosidases. The addition of phytase and protease supplements not only improves nutrient availability but also helps to mitigate environmental issues. This review provides an overview of current literature regarding the role of enzyme supplementation in optimising the sustainable use of both alternative and traditional feed resources. It describes the effects of these enzymes on pig performance, nutrient digestibility, and their broader environmental implications.