The leather industry, particularly shoe manufacturing, generates leather scraps mainly dumped in domestic or industrial waste landfills. Leather waste resulting from upper material cutting operations represents 50-70% of solid waste produced by footwear companies, resulting in around 150 000 tons of this type of waste produced annually in Europe. Vulcanized rubber is widely applied in medium to high-quality shoe soles. Leather waste fibres added to elastomers can function as short fibre reinforcement for the matrix as long as their inherent fibrous nature is maintained during processing. Studies on leather fibres show that it is possible to produce more ecological composite materials. However, the mechanical performance of these composites depends on how the leather is dispersed in the matrix and its interaction with the matrix. In this study, we report the preparation of SBR reinforced with leather waste from the shoe industry. We evaluate the effect of leather presence and the processing methodology on composites' properties. The composites were produced by vulcanization, preceded by mixing with the aid, either of a laboratory-scale open two-roll rubber mixing mill or an internal mixer machine – two practical processing techniques, versatile and compatible with large-scale industrial processes. The results indicated that the processing methodology affected the leather dispersion in the composites. The Comp20b (processed through a combination of mixing roll and internal mixer) exhibited a notoriously better leather dispersion than Comp20 (processed only by mixing roll). Both composites were reinforced with 20 parts per hundred of rubber (phr) of leather waste. Regarding the mechanical properties, Comp20b exhibited an improvement of around 13% in tensile strength when compared with pure SBR, suggesting the potential of leather waste to be used with SBR to produce composites with better mechanical properties. On the opposite side, Comp20 displayed a tensile strength of around 48% less than Comp20b, indicating that the processing methodology plays a fundamental role in the final performance of the composites.