Nanotechnology has found strong workability and applicability in various cutting-edge areas. In particular, the employment of nanomaterials in the field of agriculture and its applications has led to significant advances in the last decade, not only in food processing but also in food packaging. Building on this point, this chapter focuses on nanocomposites developed for agriculture and food applications, covering their types, methods, characteristics, functions, trends, challenges, and prospects. To narrow the focus, a special class of nanocomposites will be discussed in this report: bionanocomposites. Specifically, these materials combine biopolymers as matrices, such as polysaccharides, polycaprolactone, and polylactic acid, with nanostructures as fillers, like natural, carbonaceous metal, and metal oxide nanomaterials. These formulations can be fabricated using several physical and chemical approaches in order to ultimately acquire improved properties relevant to the target applications. In particular, bio-nanocomposites have shown superior performance when used as fertilizers, pesticides, herbicides, soil modifiers, food additives, food flavor, food colorant, or even as food packaging materials. There is no doubt that these compositions present promising alternatives to frequently used petrochemicals, such as polyethylene. More information will be provided about the role of nanofillers in addressing the drawbacks of some commonly used biopolymers, particularly in terms of physicochemical properties, including barrier, mechanical, and thermal behaviors, as well as compatibility and degradability. In conclusion, despite some limitations related to commercialization, such as concerns about nanotoxicity, government regulations, public awareness, and cost, the use of bionanocomposites could significantly contribute to sustainable food production, starting from eco-friendly cultivation and ending with the consumer. Certainly, this would have positive environmental, economic, and social impacts.