The aim of this study was to investigate the effect of a dietary probiotic supplement on bone mass and meat quality of broiler chickens. Two hundred ten 1-day-old male Ross 708 broiler chicks were divided among 21 floor pens (10 chicks per pen). The pens were randomly distributed to 1 of 3 dietary treatments containing a probiotic, Bacillus subtilis, at 0 (control), 0.25 (0.25X), and 0.5 (0.5X) g/kg (n = 7). Gait score, footpad dermatitis (FPD), leg straightness, and hock burn (HB) were examined at day 33, and a latency-to-lie test was performed at day 34. At the end of the experiment (day 35), plasma, right leg, and litter samples were collected for mineral contents, meat quality, bone morphometric parameters, and litter quality assessments. The results indicated that probiotic-fed birds stood much longer during the latency-to-lie test with a greater tibial length, weight, and strength as well as higher plasma levels of calcium and phosphorus compared with the controls. In addition, probiotic-fed birds' leg muscle had higher color lightness at both 30 min and 5 h postmortem and greater water-holding capacity with a trend for less cooking loss (P = 0.056) and lower pH values (P < 0.05) at 5 h postmortem. Probiotic-fed birds' leg meat was tastier (P < 0.05) at 24 h after slaughter. These probiotic effects were greater in the 0.5X group than in the 0.25X group. There were no treatment effects on other measured parameters including gait score, HB, FPD, tibial lateral and medial wall thickness, diaphysis and medullary canal diameters, robusticity and tibiotarsal indexes, plasma magnesium concentrations, and litter moisture and pH values (P > 0.05). These findings indicate that the probiotic supplement could be a useful management tool for improving broiler production and welfare by enhanced bone mass and meat quality.