The increasing environmental impact of petroleum-based plastic packaging has encouraged the development of biodegradable food packaging materials from renewable resources. Cassava starch is a promising biopolymer because it is abundant, inexpensive, edible, renewable, biodegradable, and capable of forming continuous films. However, native cassava starch films are often brittle and highly sensitive to moisture, limiting their food packaging applications. This study developed biodegradable food packaging films from cassava starch using glycerol as a plasticizer and plant fiber powder as a reinforcing additive. Five formulations were prepared by the solution casting method and evaluated for physical, mechanical, barrier, optical, biodegradation, and food packaging properties. The results showed that increasing glycerol concentration improved flexibility but reduced tensile strength and water resistance. The addition of plant fiber powder improved tensile strength, reduced water solubility, water absorption, and water vapor permeability, and increased opacity. Soil burial analysis confirmed progressive biodegradation over 28 days. Bread packaging tests showed that cassava starch films reduced moisture loss and delayed visible mold growth compared with unpackaged bread. The formulation containing 2% plant fiber powder showed the best overall performance, indicating its potential as biodegradable packaging for dry and short-shelf-life foods.