Background <p>The intestinal health of broilers is crucial for the efficient digestion of feed, absorption and utilization of nutrients. Synbiotics have been employed to enhance the gut health; however the optimal duration of supplementation is unclear. This study evaluated the effects of synbiotic supplementation for varying durations on broiler intestinal morphology and carcass quality.</p> Materials and methods <p>Two hundred day-old Cobb 500 broilers were randomly distributed in five treatment groups: control (fresh water) and synbiotic supplementation for 1–7, 1–14, 1–21, and 1–28 days via drinking water. Each group was replicated four times. After 42 days, four birds from each replicate were starved for 10&#xa0;h and slaughtered to investigate the carcass qualities and intestinal histology.</p> Results <p>The results showed that broiler supplemented with synbiotic for 1–14 days or longer had significantly higher breast meat yield (<i>p</i> &lt; 0.001) whereas thigh and drumstick weight were not affected by different durations of synbiotic supplementation. Dressing percentage was significantly higher (<i>p</i> &lt; 0.01) in synbiotic supplemented groups than control. In contrast, both cooking loss (<i>p</i> &lt; 0.01) and drip loss (<i>p</i> &lt; 0.05) were higher in the control group. Organ weights were mostly not affected by synbiotic supplementation. There was a significant difference (<i>p</i> ≤ 0.05) in pH of meat over 24&#xa0;h, with probiotic supplemented broiler chicks showing lower value. Additionally, the supplemented groups have significantly long ileus villus height (<i>p</i> ≤ 0.01) and significantly short crypt depth (<i>p</i> &lt; 0.05).</p> Conclusion <p>Synbiotic supplementation for one or more weeks favourlaby influences meat yield, carcass quality, and intestinal morphology in Cobb 500 broilers. The findings suggest that the duration of supplementation beyond one week provides similar benefits, indicating flexibility in synbiotc application timing beyond one week.</p>