A 28-day trial was conducted to evaluate the impact of different levels of fennel seed powder as a feed additive on the growth performance, carcass yield, internal organ characteristics, and nutrient digestibility of finisher broiler chickens. The study involved 200 finisher broiler chickens divided into four groups of 50 birds each. Four experimental diets were formulated with fennel seed powder at 0g, 150g, 300g, and 450g per 100kg of feed, labelled as T1, T2, T3, and T4, respectively. The treatment groups were further subdivided into five replicates with 10 birds in each group. Collected data were subjected to analysis of variance. The results indicated significant differences (p<0.05) in final weight gain (FWG), daily weight gain (DWG), and feed conversion ratio (FCR) among the groups. Birds in T4 group showed the highest FWG and DWG values (p<0.05). Additionally, T4 had the lowest FCR values (p<0.05), significant differences in feed intake (p<0.05) were similarly observed. Significant differences (p<0.05) were recorded in dressed weight, live weight, dressing percentage, and various cut-parts for the birds, birds in T4 recorded superior values for all carcass traits. The internal organs were not affected by the feed (p>0.05). However, the diet significantly influenced abdominal fat, with T4 showing the lowest values (p<0.05). The nutrient digestibility coefficients were significantly affected by the diet, with T4 showing the highest values in all proximate composition parameters analyzed (p<0.05). It was concluded that adding fennel seed powder at 450g per 100kg of feed can enhance the growth performance, carcass quality, internal organ traits, and nutrient digestibility of broiler chickens.