Recently, to address plastic pollution and food safety issues, the development of biodegradable materials has become a research hotspot. Cereal proteins have been widely used in natural biodegradable packaging films due to their excellent hydrophobicity and film-forming ability, including wheat gluten protein, zein, rice protein, and oat protein. Although pure cereal protein-based films have the disadvantages of insufficient stability and lack of functionality, a variety of measures have been taken to enhance the performance of the films to expand the application range of cereal protein-based films. This Review briefly reviews the fabrication process of cereal protein-based films. The interaction of various additives (plasticizers, biopolymers, nanoparticles, bioactive ingredients, and indicators) with cereal proteins is highlighted. Four methods for fabricating cereal protein-based films (casting, extrusion, electrospinning, and 3D printing) are summarized. Additionally, the impact of several novel technologies on the performance improvement of cereal protein-based films, including ultrasonic, cold plasma, and high-pressure treatment, is discussed. Finally, the application scenarios of cereal protein-based films in active and smart food packaging are discussed, and the challenges of stability and safety of these packaging films are pointed out. In conclusion, this Review identifies the development potential of cereal protein-based films in food packaging fields.