Angiotensin receptor blockers are one of the most widely used anti-hypertensive drugs which are used to reduce hypertension. In 2018, the United States Food and drug Administration together with European Medicine Agency declared that the presence of carcinogenic nitrosamine impurities such as nitrosodiethylamine (NDEA) in some of the products; including valsartan (VLS) and losartan (LOS), and drugs’ recall procedures were started. Thus, they should be controlled to be below the acceptable cancer risk level to ensure safety of the pharmaceutical products. Therefore, sensitive and reliable analytical methods were required for detection and quantitation of NDEA in bulk and finished drug products. Green analytical chemistry has received great interest to minimize the amount of organic solvents consumed without loss in chromatographic performance. For the first time, a green and sensitive HPLC method was developed for the determination of NDEA in LOS & VLS using mobile phase of 0.02M ammonium acetate adjusted to pH 7.2 and ethanol in gradient manner. LOD and LOQ for NDEA were estimated to be 0.2 and 0.5 µg mL-1, respectively. The standardized limits of NDEA impurity in drug substances were set as 0.56 ppm, which indicate the feasibility of its determination by the proposed conventional method without need for expensive instrumentations that are not available in most of pharmaceutical quality control laboratories. The method was found to have the lowest ecological impact as assessed on the Green Analytical Procedure Index greenness metric and Analytical GREEnness calculator.