Promoting exclusive breastfeeding among urban employed mothers is a complex phenomenon. Understanding the multiple level factors related to this and how they influence employed mothers' regarding exclusive breastfeeding could help identify strategies to support mothers continuing exclusive breastfeeding. This study aimed to identify maternal, social, and workplace level factors and the interaction effects among those factors that influence exclusive breastfeeding for six months among urban employed mothers. This case-control study investigated among 57 cases (exclusive breastfeeding for six months) and 228 controls (non-exclusive breastfeeding for six months) in six purposively-selected hospital settings in Bangkok, Thailand between September 2015 and June 2016. Data were collected through six self-administered questionnaires; Demographic Questionnaire, Iowa Infant Feeding Attitude Scale, Perceived Self-efficacy in Breastfeeding Questionnaire, Breastfeeding Knowledge Questionnaire, Perceived Breastfeeding Support Assessment Tool, and Infant Feeding Form, and were analyzed by descriptive statistics, univariate and multivariate logistic regression. The results revealed that maternal factors (family income, attitudes, intention, confidence, and knowledge) and workplace factors (maternity leave and working times) co-predicted exclusive breastfeeding six months. In the interaction effect model, the interaction effect between workplace policy on maternity leave and attitudes toward breastfeeding also exerted significant influence. The findings suggest that multiple level interventions to promote exclusive breastfeeding in employed women are needed. In clinical practice, nurses and midwives should implement antepartum interventions including assessment of maternal attitudes and intentions to breastfeed, providing breastfeeding knowledge to increase mothers' confidence, and advice about planning to combine breastfeeding and employment. Of great concern was a finding that more than 75% of the non-EBF mothers reported not having sufficient breastfeeding facility support in the workplace. Workplace policies should be reviewed in terms of sufficient paid maternity leave, workplace breastfeeding support, and an appropriate number of working hours, and this has implications for governments and multiple workplaces across the country. Nurses have a significant role to play in advocating for and contributing to such policies to increase the numbers of women successfully breastfeeding longer whilst employed. [ABSTRACT FROM AUTHOR]