Context The dietary inclusion of inorganic phosphates to provide dietary phosphorus, besides increasing the cost of feed, leads to the release of excess phosphorus into the environment causing pollution. Aim This study was conducted to determine the effects of dietary phytase concentration on growth, cecal short-chain fatty acid (SCFA) profile, tibia bone mineralisation, nutrient digestibility, and intestinal histomorphology of Ross 308 broilers. Methods Treatments consisted of a negative control (NC) diet containing 1.2 and 1.1 g/kg of available phosphorus (avP) for the grower and finisher periods respectively, a positive control (PC) diet containing 4.2 and 3.8 g/kg of avP for the grower and finisher periods respectively, provided via dicalcium phosphate (DCP), and DCP in the PC diet was replaced with four concentrations of phytase, namely, 500, 1000, 1500 and 2000 FTU/kg. Both NC and PC diets had the same concentrations of avP for the starter period (0–10 days). Key results At 1–41 days, bodyweight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were negatively affected in NC birds (P < 0.01). FCR was significantly lower by 3.1% and 3.7% in PC-1500 and PC-2000 birds respectively, than in PC at 1–41 days (P < 0.01). Dietary supplementation of phytase significantly increased villus height, villus width, and villus surface area in PC-2000 birds compared with the PC group (P < 0.05). A significant increase in lactic acid and total aerobic bacteria counts was observed with an increasing concentration of phytase (P < 0.01). The inclusion of phytase in the diet resulted in a notable elevation in the concentrations of acetate, propionate, butyrate, branched-chain fatty acids (BCFA), and total SCFA (P < 0.05). Conclusion In addition to enhancing growth performance, the incorporation of phytase into broiler diets with low avP can optimise intestinal morphology, regulate cecal microflora composition, and elevate the cecal concentration of SCFA. Implication Higher phytase concentration exceeding commercial recommendations are likely to have increased beneficial effects on broiler performance.