Food insecurity has prejudicial impact in protecting child undernutrition. To explore this, using nationally representative two-stage stratified sample from Bangladesh demographic and health survey 2011 data collected from mothers about their household and child born during their last delivery, a total of 5904 children having valid information of all variables selected for this study were analyzed. Following the WHO guidelines and cut-off points, the prevalence of nutritional status- stunting (40.2%), underweight (35.7%) and wasting (16.3%) were accessed by the Z-scores approach of anthropometric criterion height-for-age, weight-for-age and weight-for-height respectively. The Household Food Insecurity Access Scale (HFIAS) measure was used to measure household food insecurity in this study. Food insecurity of household was discovered to have significant impact on child undernutrition in the form of stunting (OR = 1.62, 95% confidence interval: 1.42, 1.85, p< 0.01), underweight (OR = 1.80, 95% confidence interval: 1.58, 2.06, p < 0.01) and wasting (OR = 1. 28, 95% confidence interval: 1.09, 1.51, p < 0.01). These findings persisted even after adjusted for some significant socioeconomic characteristics. It indicates that a sufficient reduction of food insecurity is obvious for protecting child from undernutrition.