This study investigated the dietary effects of Moringa oleifera leaves supplementation on egg quality, laying performance, excreta ammonia concentrations and serum biochemistry of laying chickens during the late laying period. A total of 240 64-week-old Hy-Line Brown hens were assigned to four treatment diets including Moringa oleifera leaves at 0, 3, 6 or 9 g/kg, respectively, for eight weeks. The treatments had twelve replicates with five hens each. The results revealed that incremental dietary Moringa oleifera leaves significantly increased (p < 0.01) egg weight, production, and mass through 64–68, 68–72 and 64–72 weeks of age. Simultaneously, feed conversion ratio was significantly improved (p < 0.01) with Moringa oleifera leaves supplementation compared with the control. Haugh units and the thickness of eggshells significantly improved as a response to diets supplemented with 3, 6 and 9 g/kg Moringa oleifera leaves at 72 weeks of age. Interestingly, excreta ammonia concentrations, serum cholesterol, aspartate transaminase and alanine aminotransferase significantly decreased by Moringa oleifera leaves supplementation compared with the control group. In conclusion, introducing Moringa oleifera leaves supplementation at 3, 6 and 9 g/kg increased egg production, eggshell quality, Haugh units, and decreased serum cholesterol, triglycerides, excreta ammonia concentrations besides serum liver enzymes, uric acid and creatinine. Overall, based on the observed results, Moringa oleifera leaves supplementation was very promising and these leaves could be used as an effective feed additive in laying hens’ diet during the late laying period.