Sustainable utilisation of solid waste has been influenced by the increasing population of the world. Benefits of using solid waste based on natural fibre in polymer material are biodegradability and cost effectiveness. In poultry farms, chicken poultry, one of the slaughterhouse wastes is confronted with 30 10 kg of waste per year in Turkey. The evaluation of this waste, which is quite rich in keratin, is extremely important both for the solution of the waste problem and for maintaining a clean environment, bringing this valuable material to the economy. These fibres are stable, durable and biodegradable because they have a crystalline structure. However, this valuable waste will have a positive effect when used together with boron minerals, which both increase the mechanical properties, flame retardancy and biodegradation of composite material. In this study, it is the aim to manufacture superior polyester-based composite materials reinforced with three kinds of boron minerals, such as boron oxide, borax pentahydrate, borax decahydrate and fibres recycled from waste chicken feathers. The effect of different filling ratios of filling materials on the mechanical and physical properties of composite materials was examined. Flame retardancy properties of the composites with best mechanical results were investigated. After pouring by means of the pre-casting process, the water absorption and swelling thickness of final products, as well as density, bending strength, flexural modulus, limiting oxygen index, thermogravimetric analysis and scanning electron microscope analysis, was performed. Mixing prescriptions and conditions with the best properties were determined.