Functional nanocomposites printed in three dimensions (3D) have become a cutting-edge technology with enormous potential for use in a wide range of sectors. This work offers a thorough analysis of current developments in the synthesis, characterisation, and uses of functional nanocomposites that are 3D printed. It covers cutting edge synthesis strategies, creative characterisation approaches, and a range of applications made possible by these materials. The research also outlines the difficulties that are currently being faced and the opportunities that lie ahead for the 3D printing of functional nanocomposites. Considerable progress has been achieved recently in the synthesis of functional nanocomposites specifically designed for 3D printing. Nanomaterials may now be added to printed filaments or inks via the adaptation and optimisation of conventional techniques like melt and solution mixing. Furthermore, cutting-edge methods like direct ink writing and in-situ polymerization have shown promise in precisely regulating the dispersion and alignment of nanoparticles inside the composite matrix. By using these synthesis techniques, it is possible to create nanocomposite formulations that meet particular application needs and have improved mechanical, electrical, thermal, and biological characteristics. Additionally, the synthesis of hybrid nanomaterials—which entails combining several nanoparticle forms or hybridising with organic polymers—has made it possible to create multifunctional nanocomposites with complementary qualities, broadening the range of possible uses.