This experiment was accompanied to determine the use of yeast and garlic extract mixture in broiler diets on growth performance, nutrient absorption, excreta microbiota, blood profiles, and meat quality. A total of 792 male Ross 308 broilers (1-day-old, body weight 41 ± 0.5 g, and 5 weeks trial) were randomly allocated. Birds were arbitrarily assigned to one of four nutritive treatments (11 replicates; 18 birds/replicate). A basal diet (CON) was supplemented with 0.1%, 0.2%, and 0.3% yeast–garlic mixture (YGM). Body weight gain linearly increased during the overall period and tended to increase from day 21 to day 35, while feed intake showed a tendency to increase during the overall period by YGM inclusion. However, Salmonella counts linearly decreased, but Lactobacillus and Escherichia coli counts remained unaffected. Excreta CO₂ emissions were linearly reduced; nevertheless, other noxious gas emissions were not affected. Furthermore, YGM supplementation elicited a tendency for improved lymphocytes and linearly increased IgG. However, feed conversion ratio, mortality, nutrient utilization, and meat quality were not influenced. YGM addition (0.1%, 0.2%, and 0.3%) linearly improved broiler growth performance by decreasing microbiota and gas emission and increasing blood parameters. So, the proper dose of YGM was 0.3%.