ABSTRACT The traditional rubber processing aids are mostly petroleum derivatives, which are easy to migrate from the rubber matrix. To develop environmentally friendly, bio‐sourced rubber processing aids that replace traditional petroleum‐based rubber additives, the concept of “supported biomass rubber additives” was proposed. Epoxidized soybean oil (ESO) was chemically grafted onto the silica (SiO 2 ) surface to prepare SiO 2 ‐supported processing aids (SiO 2 ‐s‐ESO). SiO 2 ‐s‐ESO showed uniform dispersion in styrene‐butadiene rubber (SBR). Moreover, the SBR/SiO 2 ‐s‐ESO composite has strong filler‐SBR interfacial interaction, as proved by the immobilized SBR chains approaching SiO 2 . Compared to SBR/SiO 2 /ESO and SBR/SiO 2 /petroleum‐based plasticizers composite, SBR/SiO 2 ‐s‐ESO composite has better processing properties, vulcanization rate, and abrasion resistance, less rolling resistance, and frictional heat generation. It is envisaged from this work that the methodology of the surface modification for SiO 2 to prepare supported biomass rubber additives can be expanded to other rubber fillers and additives. This work could help to prepare high‐performance rubber/filler composites.