The footwear industry generates significant amounts of non-biodegradable waste, particularly ethylene vinyl acetate (EVA), which is commonly used in soles and insoles. Post-industrial and end-of-life footwear waste contributes significantly to environmental pollution and public health risks, as most discarded shoes end up in landfills or incineration facilities. Therefore, it is essential to explore strategies for recycling EVA waste and encourage sustainability and circular economy in this sector. This study investigates the influence of particle size on the properties of 100% recycled EVA composites without additional binders or matrices. EVA waste used in this work was ground into four different particle sizes (0.5, 1, 2, and 4 mm) to produce composites through compression molding under equal experimental conditions. Samples were analyzed using SEM/EDS to understand the effects on composite pore size, and the thermal and mechanical properties were investigated to understand the impact of particle size on mechanical and thermal properties. The results indicate that decreasing EVA particle size enhances mechanical properties. Conversely, composites produced with larger particles show an enhancement in thermal properties. In conclusion, this study demonstrates that particle size influences the properties of 100% recycled EVA composites, offering valuable insights for developing circular economy strategies in the footwear sector.