Introduction and aim. The use of pacifier is a very common practice in the early childhood period in the world. In recent years, the harms of pacifiers have been discussed rather than their benefits. We aimed to determine the knowledge and behaviors of mothers with children aged 0–3 about the use of pacifiers. Material and methods. A cross-sectional study was conducted with 363 mothers between January 10th and November 31st, 2020 in Zonguldak, Turkey. The data were collected with a web-based questionnaire. This article was prepared following STROBE guidelines. Results. The mothers started using the pacifier for the first time when their children were at an average of 2.86±3.31 months old, and they used it for at an average of 12.06±9.13 months. Of the mothers, 36.4% were found to clean the pacifier every month and 30.6% to have the behavior of dipping the pacifier into a product such as sugar, honey, molasses, and jam. The mothers with undergraduate degrees had the behavior of cleaning pacifiers more than those with postgraduate degrees (p<0.001). Conclusion. Mothers preferred to give pacifiers to babies at a high rate and had misinformation about the use of pacifiers that may harm their children’s health.