Adequate dietary intake is important in achieving optimal nutrition and health for people before and during treatment of HIV. Inadequate nutrition causes health issues and fatalities among prisoners. Thus, this study assesses dietary intake and factors affecting food service among male prisoners living with HIV at selected prisons in Kenya. A cross sectional analytical study design was adopted on a sample of 113 male prisoners living with HIV, randomly sampled from 4 prisons. Data collection tools included a structured questionnaire used to collect demographic, 24 h recall and food frequency data. During data analysis, 24 h recall data was analyzed using Nutri-survey software, and further analysis via SPSS software. Results revealed that slightly more than half the prisoners (50.4%) were aged 36-53 years. Primary education was attained by 60.2% and secondary education by 21.2%. Mean dietary intake for macronutrients was: Energy (1815±218 Kcal), Protein (56±12 g), fat (32±6 g), Carbohydrates (322±45 g), Fiber (41±23 g) and PUFA (8±1 g). None attained Recommended Daily Allowances (RDA) for energy, fat and PUFAs. Mean key micronutrients were: Vitamin A (1195.1±812.7), Vitamin B6 (1.9±0.9), Vitamin C (55.7±18.4), Iron (10.2±2.7), Magnesium (488.1±152.3) and Zinc (13.9±6.7). None met RDA for Iron. Therefore, provision of a nutritionally balanced diet in prisons can ensure nutrients adequacy.