Onion (Allium cepa) derivatives contain bioactive compounds with antioxidant and antimicrobial properties that may improve product quality. This study evaluated the effects of onion juice (OJ) and onion chaff (OC) on the sensory, proximate, and microbial characteristics of smoked Clarias gariepinus to assess their performance in enhancing fish quality. Onions weighing 1kg were washed and blended to a paste, the pulp was transferred through a muslin cloth (1mm mesh-size) to obtain the juice by squeezing, leaving the chaff as a waste residue Thirty freshly harvested C. gariepinus (average weight 1kg) were divided into three groups of ten fish, each treated with OJ, OC, and untreated controls. All samples were smoked using a modified smoking kiln and stored at room temperature for eight weeks. Proximate composition, microbial characteristics and sensory attributes were analysed using standard procedures. Results indicated that OC-treated fish recorded higher proximate values, which differed significantly (p<0.05) from those of OJ-treated samples. Protein content decreased slightly across treatments, from 62.38% to 60.25% (OC), 60.09% to 58.05% (OJ), and 59.43% to 55.84% (control), while ash and moisture contents increased. Sensory evaluation revealed higher scores for OJ-treated fish in taste (7.90), appearance (8.05), aroma (7.80), texture (7.80), and overall acceptability (8.10) compared to OC-treated fish. Microbial organisms isolated showed varied characteristics. These findings suggest that onion derivatives enhance the sensory, nutritional, and microbial properties of smoked fish. Onion juice performed slightly better than onion chaff, suggesting its potential as a natural quality enhancer for smoked C. gariepinus.