Abstract <p>This paper investigates the impact of organic amendments and bio-fertilizers on coriander yield and essential oil composition (<i>Coriandrum sativum</i> L.). To do so, an experiment was conducted in 2019 in Tehran Province, Iran, using a randomized complete block design with twelve treatments and three replicates. Treatments comprised ten combinations of organic amendments, one chemical fertilizer treatment, and one unfertilized control. Significant differences were observed among treatments for all evaluated traits. The highest biomass yield (6416.7 kg/ha), seed yield (1297.5 kg/ha), and linalool content in essential oil (89.53%) were achieved with a combined application of Nitroxin and bio-superphosphate. Nitroxin alone yielded the highest essential oil content (0.32%) and essential oil yield (2.89 kg/ha). The bio-superphosphate treatment produced the highest γ-terpinene content in essential oil (5.29%). In contrast, the chemical fertilizer treatment led to the highest number of umbels per plant (23.6 umbels) and geranyl acetate content in essential oil (8.69%). Based on <i>k</i>-means clustering analysis, the treatments were classified into six groups. In conclusion, these results highlight the substantial role of organic amendments and bio-fertilizers in improving yield and enhancing essential oil quality in coriander.</p>