Biomass‐based plastics (BPs), produced from natural polymers using a bottom‐up strategy, have been used to alleviate the environmental pollution caused by petrochemical‐based plastics (PCPs). Such BPs, however, typically require complex manufacturing processes, resulting in higher costs and reduced eco‐friendly features. Herein, a delignification‐splicing‐based strategy without adhesives for directly converting corn (Zea mays L.) husks to corn husk‐based plastic (CHP) is described. During this process, lignin is removed from the corn husks and the pores collapse to form a dense structure. The CHP, which combines high mechanical strength (118 MPa) and a Young's modulus of  7.8 GPa with excellent light transmittance (86%), can be prepared in large sheets and can potentially replace non‐renewable, non‐biodegradable PCPs. Each hm2 of cornfield can generate 1.2 hm2 of CHP annually using the strategy. The process is simple, green, scalable, and as low cost as traditional PCPs since the only consumables are corn husks, NaClO, and water. Functional CHPs, such as fluorescent or hydrophobic CHPs, can be fabricated by impregnating delignified corn husk with carbon dots before pressing or by post‐pressing hydrophobilization, respectively. This work develops an alternative green and sustainable technology for eco‐friendly BPs, adds value to agricultural waste, and reduces greenhouse gas emissions.