This study was conducted to assess the effect of fermented soybean meal (FSBM) on growth performance, economic efficiency, and cecal microbial activity in broilers. One hundred and twenty Cobb 500 broiler chicks, one-day-old, with initial weight (44.75 g/bird) were used. In a complete randomized design, the birds were weighted and randomly assigned to six groups from T1 to T6 treated with different levels of FSBM as 0%, 2%, 4%, 6%, 8%, and 10 % respectively. For a treatment, five replicates with four chicks in each one were used. Results showed a significant increase (P < 0.05) in the body weight (BW) in T2, T5 and T6 group which increased by 16.76%, 15.77% and 17.96% than the control group, respectively. Birds fed diet contain 2% FSBM had the best feed conversion ratio (FCR) as it improved with 12.43% than the control. There was a significant increase (P < 0.05) in the abdominal fat%, liver% and heart% in T6 and no significant differences were detected in other groups compared to the control. Also T3 showed a significant increase in intestine% compared to control. The economic efficiency, net profit and total return were significantly (P < 0.05) higher in T2, T3, T5, and T6 than control group. There was a significant (P < 0.05) decrease in the number of coliform bacteria in all groups compared to the control. But there was a numerically increase in the number of lactic acid bacteria in T2 and T6 than the control. There was a significant increase in the cholesterol level in a level dependent manner. No significant differences in total protein and albumin were detected in T2 compared to control group. Collectively, our results revealed that 2% FSBM had benefit effects on growth performance of birds with a good economic efficiency.