© 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Fused deposition modeling (FDM) is one of the most widely used additive manufacturing techniques for the fabrication of polymeric parts. Earlier applications of FDM mostly utilized pure polymers such as polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS). However, there has recently been an increasing demand for composite FDM filaments to obtain superior mechanical and physical properties. Fly ash (FA), a waste of coal power plants, is a promising alternative as a filler material for developing composite filaments. Due to the massive amounts of FA generated worldwide and associated environmental concerns, there has been an increasing trend in the utilization of FA particles in the polymer industry, providing a new route for FA recycling towards reducing FA’s impact on the environment. However, there has been no study to date to investigate the same route for FDM use. In this study, we incorporated 2 wt% FA into an ABS matrix using a twin-screw extruder and produced composite filaments for FDM. The specimens printed with the composite filament were tested for their microstructural, mechanical, and thermal properties through X-ray diffraction (XRD), tensile testing, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Overall, the properties of the composite specimens are not drastically different from those made of pure ABS, except for the decrease in the elongation at break. The results demonstrate the feasibility of using ABS-FA composites in FDM as a coloring agent that contributes to the recycling of waste material at the same time.