BACKGROUND: Provision of preconception care is significantly affected by the health care provider's knowledge of preconception care. In Ethiopia, preconception care is rare, if even available, as part of maternal health care services. Thus, this study aimed to determine the level of knowledge of preconception care and associated factors among health care providers working in public health facilities in Eastern Ethiopia. METHODS: A multicenter cross-sectional study was conducted from 1 March to 1 April 2020. A simple random sampling technique was used to select a total of 415 maternal health care providers. We utilized a structured, pretested, and self-administered questionnaire to collect data. Data were entered into EpiData (version 3.1) and exported to STATA (version 16) for analysis. Descriptive statistics and bivariate and multivariate logistic regression analyses were performed. All covariates with a p value ⩽0.20 in bivariate logistic regression were entered into a multivariate logistic regression analysis to control the confounding variables; variables with a p value <0.05 were considered statistically significant. RESULTS: Out of 410 respondents, 247 (60.2%; 95% confidence interval: 55.4-65.1) had good knowledge of preconception care. Having an educational level of Bachelor of Science degree and above (adjusted odds ratio: 6.97, 95% confidence interval: 3.85-12.60), 5 or more years work experience (adjusted odds ratio: 2.60, 95% confidence interval: 1.52-4.49), working in a hospital (adjusted odds ratio: 2.50, 95% confidence interval: 1.25-4.99), reading preconception care guidelines (adjusted odds ratio: 3.06, 95% confidence interval: 1.40-6.68), and training on preconception (adjusted odds ratio: 2.90, 95% confidence interval: 1.37-6.15) were significantly associated with good knowledge of preconception care. CONCLUSIONS AND RECOMMENDATIONS: Three out of five maternal health care providers in this study had good knowledge of preconception care. Facilitating continuous refreshment training and continuous professional development for health workers, preparing comprehensive preconception care guidelines for health institutions, and reading preconception care guidelines were highly recommended.