The advent of 3D printing has revolutionized industries through rapid prototyping and customized manufacturing. ABS composites, known for their versatile mechanical and thermal traits, have gained attention for diverse applications. However, refining the surface finish of 3D-printed ABS composite parts is challenging as compared to pure material. This study explores the possibility of enhancing the surface roughness and hardness of 3D-printed ABS composites via Ultrasonic-Assisted Chemical Vapor Finishing (UACVF) process. ABS composites with copper (10% weight) are additively manufactured, followed by UACVF treatment at varying temperatures, air flow rates, and times. Through rigorous analysis using Taguchi, ANOVA and Regression techniques, it has been determined that temperature and time play pivotal roles in determining surface roughness, with temperature contributing 50% and time contributing 35% to the overall outcome. Moreover, the hardness of the 3D parts experiences a slight increase, with temperature being the primary influencing factor, contributing up to 87%, followed by time at 9%. Hence, the UACVF process is a highly effective technique that results in an ultra-smooth finish due to vibrations induced at surface of semi-molten parts while causing minimal deterioration of the upper surface.