The performance and carcass characteristics of Growing Pullets (GP) fed basil leaf (Ocimum gratissimum) (OG) supplement was studied for 8 weeks using eighty-four 13 weeks old Nera Black GP. The birds were maintained on growers diet supplemented with 4 levels of basil leaves supplement(BLS) (0, 5, 10 and 15g/bird) for treatments A, B, C and D, respectively at 3 days interval throughout the period of experiment. Each treatment was replicated thrice with seven birds per replicate in a completely randomized block design. Treatment A served as control. The birds were fed the same growers diet. Feed and water were served ad-libitum. Data were subjected to Analysis of Variance (ANOVA) and comparisons made using Duncan’s Multiple Range Test. The results of the experiment showed a significant (p<0.05) treatment effects in total feed intake, feed conversion ratio (FRC) and number of eggs laid, final live weight (FLW) and mean body weight gain (MBWG). Similar scenario was observed in dressed, breast, thigh, plucked weights and egg follicle formation. Birds in control had the highest total feed intake (TFI) (6671.55 g) and MBWG (523.84 g) compared to other treatments (B, C and D) whose values were 6644.27, 6640.29 and 6152.67 g for TFI and 483.34, 500.00 and 445.24 g for MBWG, respectively. The cost of feed consumed was best on birds fed 15gBLS (N353.04/bird) while the highest number of eggs laid was recorded in birds served 5 g(83) and 15gBLS (77) with reference to control (57). Birds served 5-15g BLS had increased liver weight (26.01, 25.01 and 27.42 g) compared to control (24.38 g), while those fed 15gBLS had reduced dressed weight (DW) (952.50 g). The best egg follicle formation was recorded on those served 5g BLS/bird. There was progressive reduction in MBWG, TFI and egg follicle with increasing weight of OG, unlike FRC and liver weight, which increased linearly. Therefore, the GP are recommended to be served 5-15gBLS/bird and later reduced to 5gBLS/bird at 3 days interval when the GP had come up to 15-20% in lay, in order to minimize further loss in weight and to improve egg follicle formation.