Researchers are focusing on the valorization of available natural resources and turning their respective byproducts into useful materials. For a sustainable environment, it is vital to extensively work on zero to insignificant waste from any food production process. The utilizing of waste which comes from agriculture streams as a secondary source can be a promising step towards the net zero approach. Rice husk is available in a large quantity due to high production of rice crop, especially in Asian countries. Moreover, long-term burning of rice waste raises greenhouse gas emissions and pollutes the air. Thus, managing rice crop residues as well as producing milled rice requires a sustainable approach. Rice husk ash, bio-silica, activated carbon, biochar etc. are made from rice husks. In order for better utilization of rice husk for different purposes, it is necessary to thoroughly study its physical and chemical properties. This chapter delves into the physical, chemical, thermo-chemical and bio-chemical properties of rice husk; a major rice milling by-product. In this chapter, moisture content, bulk density, microscopic structure analysis, thermo-chemical characterizations, physical structure, chemical composition, proximate and ultimate analysis along with antioxidant properties of rice husk are discussed in detail.