Pesticide poisoning and environmental risks have increased in response to the ever-increasing use of pesticides for agriculture and food resources. Moreover, the use of pesticides in agriculture has negative health consequences on the lives of people who live in agricultural areas. Ammonium sulfate [(NH4)2SO4] is employed as a nitrogenous fertilizer and pesticide adjuvant due to its rich nitrogen contents. However, its contamination has been associated with diverse health-related toxicities. Therefore, there is an urgent need to develop sensitive, selective, and easy-to-use sensors to detect (NH4)2SO4. In the present study, we are reporting the triazole-based chemosensor as an efficient and selective sensor for detecting (NH4)2SO4. Based on Job's plot analysis, the stoichiometric ratio between chemosensor and (NH4)2SO4 was determined to be 1:2. UV–visible spectrophotometric analysis was used for investigating the detection capabilities of the proposed chemosensor. The results revealed the chemosensor with a limit of detection (LOD) of 0.4 µM for (NH4)2SO4. The chemosensor further revealed to recognize NH4+ in the presence of other competitive pesticides selectively. The triazole-based chemosensor was applied effectively to detect (NH4)2SO4 in real water samples and fresh human blood plasma. The triazole-based colorimetric probe chemosensor with 0.4 µM LOD could potentially serve effective detector for (NH4)2SO4 in different media.