This research work aims to investigate the impact of koga irrigation scheme on farmer’s livelihood, in Mecha woreda. The study used both primary data and secondary data to answer research questions. The primary data was collected from 265(105 treated group and 165 control group) respondents using multistage sampling technique. Qualitative and quantitative methods of data analysis were used for the study. The study used descriptive, inferential, and econometrics analysis. The study undertook logit regression model to identify determinants of participation decision. Propensity score matching method was also used to analyze the impact of irrigation scheme on crop income, livestock asset, agricultural input expenditure, and assets accumulation. The result of logit regression indicated that education status of household head, family size, land size, credit, and distance from irrigation schemes were identified as determinants of irrigation in the study area. Propensity score estimation technique showed that net crop income of irrigation participant households increased on average by ETB 26,703.810 per year than non-participants and agricultural input expenditure of irrigation participant households increased on average by ETB 5,679.71 per year than non-irrigator households. Likewise asset accumulations of irrigation participants have increased on average by ETB 24,968.95 compared to non-users. In contrast, no statistically significant difference in livestock resource holding was found. So, overall it can be concluded that participation in irrigation has robust and positive effect on most of the livelihood indices and the study recommends that non- irrigators have to be addressed and encouraged to participate in irrigation to increase income and improve farm household’s livelihood.