The current trend of greening production is increasingly bringing to the fore alternative types of fillers, such as biofillers, which are obtained from renewable sources or waste [1, 2]. Unfortunately, biofillers cannot be used as majority fillers due to their incompatibility with elastomer matrices and high biodegradability susceptibility [3, 4]. Therefore, the way to their efficient industrial use leads through supplementary fillers to the commonly used inorganic fillers and the partial replacement of these fillers in the blend. The influence of Chitosan as the majority filler has been investigated and its combination with carbon black filler on the elastomeric matrix of natural rubber was investigated in the presented work. The results were compared with natural rubber blends filled exclusively with carbon black. Natural rubber blends with different content of Chitosan and carbon black and their various combinations were subjected to the determination of vulcanization parameters, mechanical properties before and after thermo‐oxidative aging, and scanning electron microscopy. Although the scanning electron microscopy analysis confirmed the expected negative impact of Chitosan as the majority filler on the tensile properties of the vulcanizate, its significant impact on the main vulcanization parameters such as scorch time and optimal vulcanization time was also demonstrated. In the case of blends with a combination of carbon black and Chitosan, it has been shown that Chitosan, in addition to the filler function, also acts as an antioxidant agent through its functional groups, limiting the process of degradation of mechanical properties of natural rubber blends due to their thermo‐oxidative aging. It can be concluded that precisely because of its antioxidant and anti‐degradation effects, Chitosan can be, in addition to carbon black filler, an excellent additional filler for elastomeric blends.