This chapter discusses the process of preparation, various applications, and the potential uses of cellulose-reinforced rubber micro- and nanocomposites. Cellulose has recently been recognized for its efficiency as a reinforcement filler and has gained prominence across diverse applications, particularly in material engineering and science. As a polysaccharide abundant in plant cell walls, cellulose-filled rubber composites as environmentally friendly due to more eco-conscious alternatives to traditional fillers such as silica and carbon black and provide vast applications for polymer products. This aligns with the growing emphasis on sustainable practices and materials in various industries, reflecting a broader societal shift toward environmentally responsible choices. The chapter centers on the general preparation process and modification of rubbery materials through the incorporation of cellulose, resulting in enhanced properties such as morphological, viscoelastic, mechanical, and biodegradability.