Halophenols (HPs) inflict adverse impacts on human and environment due to their toxic, carcinogenic as well as teratogenic properties. Additionally, it is of great importance and urgency for the development of simple, efficient and inexpensive approaches to minimize the harm of HPs. Here we report an innovatively making poison profitable method to prepare carbon dots (C-dots) using 3-bromophenol residual as a precursor. The effects of solvent and carbonization temperature on the preparation of insecticide-based C-dots were investigated. The results indicate that higher organic solvent content in solution and higher carbonization temperature are in favor of the formation of C-dots with smaller size and higher quantum yields. Meanwhile, all C-dots displayed excellent water solubility and high photostability against ionic strengths and light illumination. The possible mechanisms of polymerization and carbonization of C-dots were rationally proposed, and the incompact framework structure of C-dots was reasonably inferred by room-temperature phosphorescence measurement. Also, a kind of low toxicity, good biocompatibility and photostability C-dots, which were synthesized via a lab-leveled mimetic insecticide residuals approach, were utilized as colorless inks for printing patterns and as fluorescence probe for bioimaging. This proposed approach opened up a potential prospect to efficiently utilize pesticide residuals and other hazardous chemicals for biolabeling and bioimaging.