One of the challenges in children under two years old in Ethiopia is that malnutrition and micronutrient deficiencies such as iron, zinc and calcium, often seen throughout the country. These have negative consequences on the cognitive and physical development of children, and on work productivity later at adulthood and also may lead them death. Therefore, there is a need for sustainable methods to address these inadequacies with complementary feeding. This research aims to develop and evaluate low cost complementary foods from locally available cereals and leguemes that can prepare at house hold and commercial levels. The composite flour obtained from Haricot bean, Teff and Bulla flours were extruded by twin screw extruder at different barrel temperature (120, 140, 160°C), feed moisture content (15, 18, 21%) and blend ratio BR1 (75T:25B:10H), BR2 (75T:25B:20H) and BR3 (75T:254B:30H) at constant screw speed (270 rpm). The Standard methods and analytical procedures were used to analyze dependent variables (responses). Experimental study was performed using response surface methodology central composite Design-Expert software version 7.0.0. and results were expressed as means ±standard deviation and analyzed by using (SAS). The predicted numerical optimization conditions were blending ratio of 24.65 %(BR), barrel temperature of 160°C (BT) and feed moisture of 15%(FMC) having a desirability value of 0.661. The optimum energy content of complementary foods was (348-kcal/100g) and protein was (13.87%.) moreover, the optimum WSI (36.7119%), WAI (4.4088g/g), and Viscosity (2152.11cps). similarly, iron 13.08±0069mg/100g, Zinc 6.02 ±0013mg/100g, and calcium 164.26±0.0032mg/100g respectively. Tannin and phytate were found to be 12.73±0.0043mg/100g and 45.08±0.0034 mg/100g) respectively. The sensory quality of the products was acceptable. Therefore, extruded complementary food can be developed from bulla, teff and haricot bean mixture to provide essential nutrients that are required for better growth and development of infants and children.