One important strategy for developing high performance smart materials is to utilize the magnetic properties of elastomers. Here we prepared magnetic elastomer nanocomposites using the latex compounding method followed by in situ methods. Our strategy exploited the synergetic effect of carbon nanofibers (CNFs) and ferric oxide (Fe₂O₃), which, when combined, can improve the dispersion within the elastomer matrix by introducing hybrid nanomaterial networks. When Fe₂O₃ decorated CNFs (CNF–Fe₂O₃) were embedded in an SBR matrix, they produced a remarkable improvement in the composite material's mechanical and thermal properties. This was attributed to the efficient dispersion of the CNF–Fe₂O₃, and the enhanced interfacial interaction between the filler particles and the elastomer matrix. Furthermore, the magnetic properties of the elastomer nanocomposites were modulated by the addition of the prepared CNF–Fe₂O₃ hybrids. The synergistic reinforcement of SBR achieved by the incorporation of CNF–Fe₂O₃ hybrids can support the development of high performance magnetic elastomers for applications in electronic appliances, magnetoresistive sensors, actuators, and automotive parts.