Paper has become one of the most promising substrates for building low‐cost and powerful sensing platforms due to its self‐pumping ability and compatibility with multiple patterning methods. Paper‐based sensors have been greatly developed in the field of environmental monitoring. In this review, we introduced the research and application of paper‐based sensors in environmental monitoring, focusing on the deposition and patterning methods of building paper‐based sensors, and summarized the applications of detecting environmental pollutants, including metal ions, anions, explosives, neurotoxins, volatile organic compounds, and small molecules. In addition, the development prospects and challenges of promoting paper‐based sensors are also discussed. The current review will provide references for the construction of portable paper‐based sensors, and has implications for the field of on‐site real‐time detection of the environment.