Keratinase are proteolytic enzymes that have received a lot of interest for their ability to transform the keratinous wastes that are a major source of environmental pollution. The most effective isolate that produced more keratinase was Malbranchea cinnamomea CBS 343.55. The enzyme activity was higher at 37 °C, pH 5.6; the incubation period was 7 days; and 1.0 ml was found to be the best inoculum size for keratinase production. Under solid substrate cultivation, the best substrate loadage for maximal keratinase production was 3.0 g/500 ml conical flask for M. cinnamomea CBS 343.55. The purified keratinase was stable between pH 3 and 8 and stable at temperatures ranging from 40 to 90 °C, with optimal activity at 45 °C and pH 8. The relative activity of keratinase was raised in the presence of the ions Na+, Mg2+, Mn2+, Ca2+, Co2+, Fe2+, Fe3+, and mercaptoethanol, but decreased in the presence of Hg2+, Zn2+, Cu2+, Ag2+, pb2+, ethylenediaminetetraacetic acid, and phenylmethylsulfonyfluoride. Chicken feather hydrolysate of M. cinnamomea produced total amino acids (329.0 mg/100 mL). In soil treated with feather compost and a fungus strain, there was a rise in the level of N, P, and K. However, the feather compost had a favorable impact on the growth, relative water content, photosynthetic pigments, antioxidant activity, total phenol and proline content of Vicia faba plant. In conclusion, the present study revealed that M. cinnamomea CBS 343.55O has potential applications in the biodegradation of chicken feathers and the value-addition of poultry waste as a biofertilizer.