Background: In recent decades, many attempts have been made to develop non-surgical and minimally invasive approaches to remove bulging lower eyelid fat, but there are no promising methods. Objectives: This study aimed to evaluate the efficacy and safety of treating lower eyelid fat bulging with ultrasound-assisted lipolysis (UAL) by performing a preclinical evaluation of the procedure on a Yorkshire pig. Methods: Two white Yorkshire pigs had lower eyelid fat bulging treated with UAL using a probe with a diameter of 1.0 mm or less. Fourteen days after treatment, we evaluated the changes in fat thickness from ultrasound, changes in skin contour from the Antera 3^TM, and the disruption of fat cells and changes in collagen synthesis from histological evaluation. Results: Fourteen days after treatment, the fat layer was significantly reduced with no damage to the skin surface. The mean change in the subcutaneous fat layer thickness was decreased from 1.51 to 0.75 mm in ultrasound analysis. The skin contour of the treated area also decreased with time from 202.5 to 163.5 mm in mean volume and from 0.8111 to 0.646 mm in mean height. Masson's trichrome staining showed that the UAL treatment induced the regeneration and remodeling of collagen. Conclusion: UAL may be a beneficial and well-tolerated treatment option for lower eyelid fat bulging.