Background. Preconception healthcare is promising to improve the reproductive health status of women and couples if they receive care three months to two years before conception. In the current context of Ethiopia, however, preconception healthcare is overlooked in the continuum of care. Therefore, this study aimed to assess the knowledge of preconception healthcare and associated factors: a study among mothers in Jinka town, southern region, Ethiopia. Methods. A community-based cross-sectional study was employed among 522 randomly selected women of childbearing age who are living in Jinka town from March to April 2018. The study considers all the kebeles in the town. Study subjects were determined using proportionate-to-population size allocation. Then, a systematic random sampling technique was applied. Data were collected using a semistructured and pretested questionnaire. Descriptive summary data and binary logistic regression analysis were carried out to identify factors with the 95% confidence level and a p value of less than 0.05. Results. A total of 513 study subjects participated in this study. The overall preconception healthcare knowledge score of women in Jinka town was 51.1%. In the multivariable analysis, housewives (AOR = 2.93; 95% CI: 1.38–6.19), an education level of at least college (AOR = 3.79; 95% CI: 1.75–8.23), no history of neonatal death (AOR = 4.13; 95% CI = 1.39–12.25), and the use of family planning methods (AOR = 2.38; 95% CI: 1.49–3.79) increased the probability of preconception healthcare knowledge compared to the counterparts. Conclusion. In this study, women’s knowledge of preconception healthcare was found borderline. The identified factors were housewife, education level of at least college, no history of neonatal death, and using family planning methods. Therefore, emphasizing these factors for the enhancement of women’s knowledge of preconception healthcare is a necessary step.