Biodiesel is a well-established biofuel that contains unsaturated and saturated fatty esters, and their contents influence oxidation stability and solidification properties, respectively. Also, these properties can be aggravated during use after long-term storage. In this research, a new class of antioxidant/antifreeze bifunctional additives was developed by copolymerization of monomers containing an active site for addition reactions. Hydroquinone was added to these active sites after polymerization, and this chemical modification improved the performance of the additive as an antioxidant and pour point depressant of soybean oil biodiesel. This unique class of bifunctional additives was more soluble in biodiesel than hydroquinone and polymethacrylates at the same molar concentrations. The best performance was obtained by poly(oleyl acrylate-co-stearyl acrylate hydroquinone), which improved the pour point of neat biodiesel (B100) by 10 degrees C using a charge of just 1000 mg/kg. Also, hydroquinone performed as good as dodecyl acrylate as the pendent group, hindering crystal growth while improving B100 oxidation stability.