Graphene-based materials (GBMs) possess remarkable physiochemical properties, making them promising for diverse applications in biomedicine, agriculture, food, and industrial applications. Human and environmental exposure to GBMs is increasing at an unprecedented rate, yet there is still a knowledge gap regarding the safety of GBMs. This review summarizes the physiochemical properties of GBMs and critically examines the possible effects of GBMs, both at the level of molecular mechanism and at the level of the organism. While oxidative stress-mediated cell damage has been proposed as a primary cytotoxicity mechanism for GBMs, various in vivo biodistribution and cytotoxicity mechanisms are also highlighted. This review of the literature provides an overview of the cytotoxicity of GBMs, raising concerns about their widespread application with potential hazardous consequences on the environment and in human health.