Improving oil recovery from hydrocarbon reservoirs is a significant goal in the petroleum industry, particularly from an economic perspective. Over the past two decades, the influence of nanotechnology and sonic wave irradiation methods on crude oil properties has been well established. Among these, carbon nanoparticles have demonstrated a notable impact on fluid-rock interactions within reservoirs. This study thoroughly investigated the combined effects of carbon dots (CDs) and ultrasonic waves (USW) on wettability and interfacial tension (IFT) between fluids and rocks. The synergistic application of CDs and USW was found to reduce oil viscosity by 58%, from 230 cP (crude oil) to 96 cP, at an optimal CD concentration of 0.08 wt%. Additionally, the simultaneous use of CDs and USW decreased IFT by 42%, from 43 to 25 dyne/cm, enhancing the solubility between oil and water. This IFT reduction is attributed to the combined effect of CDs and USW in lowering oil viscosity, reducing heavy crude oil components, and modifying interfacial interactions between crude oil and rock. The study also revealed that the concurrent use of CDs and USW increased the contact angle between crude oil and rock surfaces from 30° to 73°, thereby reducing the rock’s oil adsorption tendency. These findings highlight the dual role of CDs in breaking down heavy oil components and modifying interfacial properties at the rock-fluid interface, leading to enhanced oil mobilization. Furthermore, USW alone was found to decrease oil viscosity and IFT by 44% and 14%, respectively. The results suggest that the combined application of USW and CDs holds great potential for industrial applications, including enhanced oil recovery and crude oil transportation, to optimize oil production efficiency.