Abstract This study investigated the potency of bird eye pepper of varying proportion and sieve size on growth performance and meat quality of broiler chickens. Two hundred and forty-six (246) two-week old broiler chicks were randomly allotted to six treatment groups (basal diet (B) inclusive x 2) in a 2 X 3 factorial arrangement each replicated four times (10 x 10 x 10 x 11) in a completely randomized design. Diets-containing BEP of varying proportion (0, 150 and 300 g) and sieve size (0.05 and 0.1 mm) were offered in two phases, starter (14 days) and finisher (17 days). Post-feeding, 48 birds (two per replicate) were sacrificed to further evaluate performance and assess the quality of meat produced. Result obtained indicate chicks fed 150 g BEP consumed less feed compared to 300 g BEP. Also, 0 and 150 g BEP groups had better (P <0.05) FCR than 300 g BEP, while 0.05 mm BEP diet improved (P < 0.05) FCR as against 0.1 mm BEP. Interaction of proportion and sieve size effects of BEP increased (P < 0.05) the final weight of the birds and suppressed (P < 0.05) feed intake for all groups as against 300 g (0.1 mm) BEP (1576.00 g/bird; 964.20 g/bird). Feeding 150 and 300 g BEP diets lowered (P < 0.05) super oxide dismutase (SOD) production compared to 0 g BEP, while 150 g BEP diet increased (P < 0.05) catalase production over 0 g BEP. Interactive effect of proportion and sieve size of BEP reduced (P < 0.05) SOD production in 150 g (0.05 & 0.1 mm) BEP and 300 g (0.05 mm) BEP groups, followed by 300 g (0.1 mm) BEP group that had lower (P < 0.05) SOD than both basal groups. Birds fed B + 150 g (0.05 mm) BEP diet produced more (P < 0.05) catalase compared to both basal groups. Meat pH for 150 and 300 g BEP groups was significantly (P < 0.05) reduced than 0 g BEP. This study has shown BEP at low concentration (150 g) screened with 0.05 & 0.1 mm sieves enhanced chick welfare, while a higher concentration (300 g) screened at 0.05 mm improved overall growth performance (endogenous-antioxidant profile) at finisher phase. Broiler chickens, farmers and meat processors will benefit from diet-containing BEP screened through 0.05 mm sieve.