Changes in climatic conditions pose a threat to food systems and livelihoods, particularly in areas dependent on rain-fed agriculture. Therefore, this study aimed to identify the factors influencing small-scale irrigation adoption by farmers in the Gambella region. The Abol, Itang, and Makuey districts were selected purposively, and three kebelles, namely, Bonga, Achewa, and Adura, were selected using the probability proportional to size sampling technique. A stratified sampling technique was used to select the target participants as adopters and non-adopters. The collected data were analyzed using descriptive and inferential statistics and econometric models. The study found that 51.7% of the farmers did not apply any irrigation, 25.4% practiced surface irrigation, 7.5% used motor pump irrigation, and 11.7% used manual watering. Only 3.8% of farmers used solar energy irrigation for sustainable agriculture. The binary logit model analysis results found that access to farm inputs (P < 0.05), credit access (P < 0.01), farmland ownership (P < 0.01), on-farm income (P < 0.05), and farming training center access (P < 0.05) significantly and positively influenced the farmers’ adoption of small-scale irrigation. Distance to market (P < 0.01) and distance to water sources (P < 0.01) significantly and negatively influenced adoption. The findings suggest that strengthening institutional support, access to finances, and input availability, while reducing physical barriers, is essential for improving farmers’ small-scale irrigation adoption and fostering their resilience to climate variability in the region.