Background According to the Lancet, the successful chemoprophylaxis and the introduction of lifelong antiretroviral therapy programs to eliminate mother to child transmission of HIV has promoted the rise in number of HIV exposed uninfected (HEU) infants. In resource limited settings, these infants are at an increased risk of undernutrition due to risk factors such as low birth weight, food insecurity, household composition, income and improper feeding patterns. As several other studies have suggested, the risk factors vary from one setting to another. This paper delved into reviewing the predisposing undernutrition factors in relation to HIV exposure among infants within the low resource urban setting of Mukuru Slum, in Nairobi, Kenya. Methods A retrospective cohort study was performed on 160 mother/guardian-child pairs in Mukuru Slum, Nairobi, Kenya. Growth charts of the HIV exposed uninfected infants were studied against a control group of HIV unexposed uninfected infants (HUU). Interviews to collect information on socio economic status, household composition, HIV exposure, infant feeding practices and food insecurity related challenges were done. Data was analyzed using IBM SPSS version 20 and WHO anthroplus software. Descriptive statistics as well as Chi square, t-tests and multivariate analysis was done. Results Stunting among the HIV exposed uninfected infants was the most common form of undernutrition. 38.9% of the HEU infants were severely stunted (LFAZ), while 5.6% of them were severely wasted (WFLZ), while 24.4% of them were severely underweight. The mean birth weights of the HEU infants (2.953kg ) was lower than the HUU (3.195kg). HIV exposure was associated with lower Weight for Length Z score (WFLZ), Weight for Age Z score (WFAZ), Length for Age Z score (LFAZ), BMI for Age Z score (BAZ) and Middle Upper Arm Circumference Z score (MUACZ) (p<0.001) . HEU infants were more likely to live in households with lesser number of adults (p=0.016) and higher number of children (p<0.001) as compared to the HUU. Although exclusive breastfeeding was upheld among all infants, the HEU were more likely to rely on Food by Prescription supplements (p<0.001) to meet their daily energy needs. Households with HEU infants were, however, less likely to receive food (p=0.041). Overall the largest effect sizes on undernutrition of all infants was found to be affected by the age of children (η p 2 =0.439; p<0.001) , sex (η p 2 =0.135; p=0.001) , HIV exposure ...