Chronic food insecurity remains a critical challenge among agro-pastoral households in the Afar region of Ethiopia, primarily due to recurrent droughts, climate variability, and dependence on rain-fed agricultural systems. Although the Gewane district possesses substantial irrigation potential, its utilization remains below capacity, and empirical evidence on the relationship between small-scale irrigation participation and household food security in this specific context is limited. This study, therefore, aimed to analyze the impacts of small-scale irrigation participation on agro-pastoral households' food security, identify factors influencing participation in irrigation farming, examine determinants of irrigation participation intensity, and evaluate the impact of irrigation on food security outcomes. A multi-stage sampling procedure was employed to select 356 households, 186 irrigation users and 170 non-users from three kebeles in the Gewane district, Afar region, Ethiopia. Primary data were collected using structured questionnaires. Descriptive statistics, a Double-Hurdle model, and Propensity Score Matching with a kernel matching bandwidth of 0.1 were applied to estimate average treatment effects. Food security was measured using daily calorie intake per adult equivalent against the national threshold of 2100 kcal, and data analysis was conducted using STATA version 16. The probit model results indicated that sex of the household head, livestock ownership, education, farm size, farming experience, distance to irrigation water source, and off-farm income significantly influenced irrigation participation at (p<0.01) and (p<0.05) significance levels, respectively. The truncated regression revealed that farm size, extension contacts, education, dependency ratio, livestock holding, and distance to irrigation significantly affected the intensity of participation at (p<0.01) and (p<0.05) significance levels, respectively. Propensity Score Matching estimates showed that irrigation participation increased daily per capita calorie intake by 803.05 kcal (ATT = 803.05, t = 10.06) relative to nonparticipants. Furthermore, net grain availability for irrigation user households was 2727.16 kcal, more than double that of non-users (1290.33 kcal). It is concluded that small-scale irrigation participation significantly enhances household food security among agro-pastoral households in the study area. Strengthening extension services, improving access to credit, and training households on irrigation interventions are recommended.