3D printing has become a popular fabrication technique for rapid prototyping of complex structures in recent years due to its simplicity, relatively short production time and low material wastage. Despite these advantages, it remains difficult to fabricate structures out of composite materials, such as nanofiller-reinforced polymer resins, using 3D printing. Here, we investigate the factors influencing the stereolithographic synthesis of 3D structures, such as concentration of filler and post-fabrication baking temperature and duration, and demonstrated, for the first time, the successful fabrication of 3D graphene-polymer composite lattices. Quasistatic mechanical tests showed that the stiffness of a polymer, reinforced with as little as 0.02 wt. % graphene, can increase up to 70.2 % compared to a non-reinforced polymer. Furthermore, enhanced energy absorption was also observed for octet-truss lattices 3D printed from the polymer-graphene composite material. In situ microscopic deformation and failure of the 3D printed graphene-polymer composite during mechanical testing will be presented and discussed as well.