With the rapid expansion in the nanotechnology industry, it is essential that the safety of engineered nanomaterials and the factors that influence their associated hazards are understood. A vital area governing regulatory health risk assessment is genotoxicology (the study of genetic aberrations following exposure to test agents), as DNA damage may initiate and promote carcinogenesis, or impact fertility. Of late, considerable attention has been given to the toxicity of engineered nanomaterials, but the importance of their genotoxic potential on human health has been largely overlooked. This comprehensive review focuses on the reported abilities of metal nanoparticles, metal-oxide nanoparticles, quantum dots, fullerenes, and fibrous nanomaterials, to damage or interact with DNA, and their ecogenotoxicity is also considered. Many of the engineered nanomaterials assessed were found to cause genotoxic responses, such as chromosomal fragmentation, DNA strand breakages, point mutations, oxidative DNA adducts and alterations in gene expression profiles. However, there are clear inconsistencies in the literature and it is difficult to draw conclusions on the physico-chemical features of nanomaterials that promote genotoxicity, largely due to study design. Hence, areas that require that further attention are highlighted and recommendations to improve our understanding of the genotoxic potential of engineered nanomaterials are addressed.