Over 40% of the current world conventional oil production comes from carbonate reservoirs, dominantly mature and declining giant oilfields. After primary and secondary oil production stages using tertiary oil production methods as part of an enhanced oil recovery (EOR) scheme is inevitable. Surfactant flooding aims at reducing the mobility ratio through lowering the interfacial tension between oil and water and mobilizing the residual oil. This article highlights the adsorption equilibrium of the combination of different types of nanosilica and Zyziphus Spina Christi, a novel surfactant, in aqueous solutions for EOR and reservoir stimulation purposes. A conductivity technique was used to assess the adsorption of the surfactant and nanosilica in the aqueous phase. Batch experiments were used to understand the effect of adsorbent dose on sorption efficiency as well. The adsorption data were examined using four different adsorption isotherm models (Langmuir, Freundlich, Temkin, and Linear), and the adsorption parameters were determined for each model. This study suggests that a Freundlich isotherm model can satisfactorily estimate the adsorption behavior of combination nanosilica and surfactant adsorption on carbonates. Results from this study can help in appropriate selection of surfactants in the design of EOR schemes and reservoir stimulation plans in carbonate reservoirs.