Palm kernel meal (PKM) has potential to be used as dietary protein source for soybean meal substitution in broiler diets. However, high mannan content limits PKM utilization in feed formulation due to low digestibility. This study evaluated the effect of endo-1,4-β-mannanase enzyme on performance and carcass traits of broilers fed palm kernel meal and hydrolyzed palm kernel meal (HPKM). A total of 1,050 day-old chicks were allocated into six treatments with five replicates (n = 35). Starter phase: 1) CON (control); 2) PKM1 (1%); 3) HPKM1 (1%); 4) PKM2 (3%); 5) HPKM2 (3%); and 6) COMB (3% PKM + 3% HPKM). Grower phase: 1) CON (control); 2) PKM1 (2%); 3) HPKM1 (2%); 4) PKM2 (7%); 5) HPKM2 (7%); and 6) COMB (3.5% PKM + 3.5% HPKM). Finisher phase: 1) CON (control); 2) PKM1 (3%); 3) HPKM1 (3%); 4) PKM2 (10%); 5) HPKM2 (10%); and 6) COMB (5% PKM + 5% HPKM). Supplementation of endo-1,4-β-mannanase enzyme was 2 g/kg on PKM1 and HPKM1, and 3 g/kg on PKM2, PKH2, and COMB. The results showed that PKM and HPKM supplemented endo-1,4-β-mannanase enzyme did not influence feed intake (FI), BW, or feed conversion ratio (FCR) in the starter and grower phase. Dietary PKM and HPKM decreased BW compared with control (P<0.001), although FI and FCR did not differ in the finisher phase. In addition, higher inclusions of PKM and HPKM (e.g., PKM2, HPKM2, and COMB) had lower slaughterhouse weight (P=0.002), carcass yield (P<0.001), breast yield (P=0.02), and breast pH (P<0.05) compared with CON, PKM1, and HPKM2. Dietary PKM and HPKM also tended to reduced meat tenderness (P=0.060), but did not affect meat cooking loss or water holding capacity.