Abstract: One hundred day-old Anak broiler chicks were used to evaluate the optimum inclusion levels of Fermented Parkia Biglobosa Seed Meal (FPSM) based diets on Body Weight Gain (BWG), feed intake, Feed Conversion Ration (FCR), Protein Efficiency Ratio (PER), Apparent Digestibility Coefficient (ADC), carcass and organs weight and cost/ benefits of finisher broilers. The birds were randomly allotted to five dietary treatments of 20 birds each, replicated two times per treatment with 10 birds each in a Completely Randomized Design (CRD). Each treatment contained 0, 25, 50, 75 and 100% FPSM replacement for groundnut cake. Results showed that the Body Weight Gain (BWG) was significantly (p<0.05) improved with FPSM inclusion levels in the diet. The BWG was significantly (p<0.05) higher at 100% FPSM when compared with the control and others diet. The feed intake was reduced at 75% FPSM and highest at 0% FPSM (control) diet. The FCR and PER were better at 100% FPSM dietary inclusion with values of 1.59 and 2.93, respectively. The ADC of crude protein, crude fibre and ether extract were similar (p>0.05) at 0, 25, 50, 75 and 100% FPSM but significant (p<0.05) differences existed among 0, 25 and 50, 75, 100% FPSM dietary inclusion levels. The ash digestibility was highest at 50% FPSM inclusion level and least in control diet but not significantly affected (p>0.05). Carcass and organs weight (liver and gizzard) significantly (p<0.05) increased with increased FPSM dietary inclusion levels while the organ weights (Lungs, spleen, heart and kidney) where similar (p>0.05) among the dietary treatment groups. The abdominal fat deposit was highest at 50% diet and least from the 0% (control) diet. The cost/benefits of production was significantly (p<0.05) save with FPSM dietary inclusion levels in order of 100, 75, 50, 25, 0%, respectively. It was concluded that FPSM could replace GNC up to 100% with reduce cost and without adverse effect on growth performance, digestibility and organs weight.