BACKGROUND Stunting remains a major public health concern in Nepal as it increases the risk of illness, irreversible body damage and mortality in children. Public health planners can reshape and redesign new interventions to reduce stunting and severe stunting among children aged less than 5 years in this country by examining their determinants. Hence, this study identifies factors associated with stunting and severe stunting among children aged less than five years in Nepal. METHODS The sample is made up of 2380 children aged 0 to 59 months with complete anthropometric measurements from the 2011 Nepal Demographic and Health Survey (NDHS). Simple and multiple logistic regression analyses were used to examine stunting and severe stunting against a set of variables. RESULTS The prevalences of stunting and severe stunting were 26.3% [95% confidence Interval (CI): 22.8, 30.1] and 10.2% (95%CI: 7.9, 13.1) for children aged 0-23 months, respectively, and 40.6 (95%CI: 37.3, 43.2) and 15.9% (95%CI: 13.9, 18.3) for those aged 0-59 months, respectively. After adjusting for potential confounding factors, multivariable analyses showed that the most consistent significant risk factors for stunted and severely stunted children aged 0-23 and 0-59 months were household wealth index (poorest household), perceived size of baby (small babies) and breastfeeding for more than 12 months (adjusted odds ratio (AOR) for stunted children aged 0-23 months = 2.60 [95% CI: (1.87, 4.02)]; AOR for severely stunted children aged 0-23 months = 2.87 [95% CI: (1.54, 5.34)]; AOR for stunted children aged 0-59 months = 3.54 [95% CI: (2.41, 5.19)] and AOR for severely stunted children aged 0-59 months = 4.15 [95% CI: (2.45, 6.93)]. CONCLUSIONS This study suggests that poorest households and prolonged breastfeeding (more than 12 months) led to increased risk of stunting and severe stunting among Nepalese children. However, community-based education intervention are needed to reduce preventable deaths triggered by malnutrition in Nepal and should target children born to mothers of low socioeconomic status.