Hybrid filler reinforcement is another fascinating technique used to combine properties of one or more fillers in the composite. In polymer composite, a symbiotic phenomenon due to the combination of different fillers, which is also known as the synergistic effect, can greatly enhance physical properties. Carbon black is always considered the most commonly consumed reinforcing filler in the rubber industry. Considering its problems such as its non-renewable petroleum origin, dark color, contamination and pollution, researchers are seeking an adequate alternative. The mechanical and sorption properties of natural rubber reinforced with hybrid fillers were investigated. The particle size of the fillers was 75 μm. They were used in compounding natural rubber by varying hybrid filler loadings (0/60, 10/50, 20/40, 30/30, 40/20, 50/10 and 60/0) for carbon black/palm kernel and palm kernel shell/sandbox seed shell, using two roll mill. The results showed that incorporation of these hybrid fillers into the rubber matrix increased the tensile strength, tensile modulus, and hardness of the composites produced at hybrid filler loadings (0/60, 20/40, 30/30, 40/20, 50/10 and 60/0 for carbon black/palm kernel shell (CB/PKS) and 0/60, 20/40, 50/10 and 60/0 for carbon black/ sandbox shell (CB/SS) whereas the elongation at break, abrasion resistance and compression set decreased at these hybrid filler loadings. CB/PKS hybrid filled vulcanizates showed better mechanical properties than CB/SS hybrid filled vulcanizates. CB/SS hybrid filled vulcanizates had low swelling parameters (swelling ratios, swelling coefficients and mol% uptakes) than the CB/PKS hybrid filled vulcanizates. The CB/PKS hybrid filled vulcanizates, at 0/60, 10/50 and 60/0, the swelling parameters (swelling, swelling coefficient and mol% uptake) were low when immersed in diesel but at 20/40, 30/30, 50/10 and 60/0 when also immersed in fuel, the smelling parameters were also. The CB/SS hybrid filled composites at 20/40, 40/20, 50/10 and 60/0 the swelling parameters were also low when the samples were immersed in diesel and fuel. CB/PKS hybrid filled vulcanizates showed the better mechanical properties than CB/SS hybrid filled vulcanizates. CB/PKS hybrid filler could stand to be potential reinforcing filler for rubber compounds especially for articles requiring high mechanical strength while CB/SS hybrid filler for articles requiring less mechanical strength.