Breast milk is the best food and the safest option to ensure good health and ideal growth ofrnyoung children. Exclusive breastfeeding indicates that a child should be fed breast milk alonernduring the first six months of life. However, 41% of Ethiopian infants do not receivernexclusive breastfeeding and the median duration of this breastfeeding was 2.9 in months inrnAddis Ababa. Therefore, this study aims to determine the practice and associated factors ofrnexclusive breastfeeding focusing on working mothers in Bole and Addis Ketema sub-cities,rnAddis Ababa, Ethiopia. An institution-based cross-sectional study was conducted among 389rnrandomly selected breastfeeding mothers with infants aged 6 to 11-months old from June tornJuly 2020. A semi-structured interview-based questionnaire was used for data collection. Therndata were entered and analyzed using STATA version 14.2 and R version 3.6.1. Descriptivernstatistics, t-tests for difference of proportions, and multilevel binary logistic regression werernapplied in the analysis. A total of 389 (192 formally and 197 informally employed) mothersrnwere interviewed. The overall mean and median duration of exclusive breastfeeding was 127rnand 120 days, respectively. The prevalence of exclusive breastfeeding practice for allrnworking mothers was 46.53% (40.10% formally and 52.79% informally employed). Thernmultilevel analysis revealed that working mothers with cesarean delivery (AOR = 0.32, 95%rnCI: 0.184, 0.563), low birth weight (AOR = 0.30, 95% CI: 0.134, 0.689), and insufficientrnmilk production (AOR = 0.364, 95% CI: 0.216, 0.614) were significantly less likely tornengage in exclusive breastfeeding while mothers with high breastfeeding support (AOR =rn12.03, 95% CI: 5.593, 25.910) was significantly more likely to engage in exclusivernbreastfeeding. Maternal type of employment (being formal and informal) showed an effect onrnexclusive breastfeeding with intra-class correlation (ICC) = 0.0632 (0.0067, 0.4006). Thernoverall median duration of EBF was short. However, informally employed mothers breastfedrnbetter than formally employed ones. Therefore, there is a need in providing childcare servicesrnin the workplace, working on breastfeeding support, and designing strategies to better supportrnformally employed mothers are recommended.