Fused filament fabrication (FFF) is a commonly adopted additive manufacturing technique which allows direct assembly of intricate 3D multi-material components at high resolution and low cost. The aim of this research is to explore FFF processes and their unique capabilities in development of highly efficient thermoelectric (TE) energy harvesting material systems. Adapted fused filament fabrication with customized filaments produced samples with ABS (acrylonitrile butadiene styrene) polymer matrix and Bi₂Te₃ as the thermoelectric agent. Mixtures were initially extruded into composite thermoelectric filaments, which were subsequently printed into shapes and sintered in a tube furnace under inert gas environment. Thermoelectric performance characterization of the samples revealed that a maximum figure of merit of 0.54 was achieved at the sintering temperature of 500 °C for room temperature operation. This conversion efficiency was nearly five times higher than those of previously reported additively manufactured thermoelectric materials. The FFF method was therefore proven as a versatile method to fabricate efficient thermoelectric materials in intricate geometries.