Abstract: Bacillus sphaericus was isolated from naturally fermented soybeans (Glycine max) and used as a single starter for controlled laboratory fermentation for soy iru production at 35oC for 72 hours and the result of proximate analysis obtained before and after fermentation showed that, the moisture content of the boiled unfermented was 59.16% and increased slightly to 59.40% in naturally fermented soybeans and reduced to 49.99% in soybeans fermented with B. sphaericus. There was increase in percentage protein content from 24.50% to 31.24% after natural fermentation and 42.39% in control fermentation. The fat content increased from 17.12% to 19.90% after natural fermentation and 24.68% in controlled fermentation. There was increase in ash content from 0.97% to 1.72% and 9.58% of boiled unfermented, naturally fermented and controlled fermented sample. The fiber content reduced in fermented sample from 3.85% to 3.47%, and increased to 9.20% in controlled fermented sample while there was reduction in carbohydrate content from 26.30% to 22.86% in fermented and 18.12% in controlled fermented sample.