Background: To determine the frequency of breastfeeding of mothers working in primary care, the differences between different employment groups, and the effective factors. Methods: This descriptive research study was conducted with a self-report online survey design. The snowball sampling method was used for the sample selection, and 151 family physicians and 126 family health professionals were included in the study during the research period (June 2019-December 2019). A 35-item survey was used to collect data. The response rate was 44.9% (49.5% family physicians/40.3% family health professionals). Results: The mean duration of exclusive breastfeeding was 3.9 ± 2.0 months, and the mean duration of total breastfeeding was 16.7 ± 8.5 months. There was no significant difference between the family physicians and family health professionals in terms of exclusive breastfeeding (P = 0.580) and total breastfeeding (P = 0.325) durations. The most common reasons for weaning was reduced milk supply (25.6%) and not being able to use breastfeeding leave (23.1%) due to problems at work. Of the sample, 41.3% had problems with their co-workers and 41.9% had problems related to patient care when taking breastfeeding leave. Working in a baby-friendly center (P = 0.010), prolonged exclusive breastfeeding (P < 0.001), and increased hours of breastfeeding leave taken (P = 0.001) had a positive effect on breastfeeding for ≥24 months while experiencing problems with co-workers in taking breastfeeding leave (P = 0.023) had a negative effect on this variable. Conclusions: All of the factors that were determined to affect the continuation of breastfeeding for ≥24 months are modifiable. It is very important for relevant authorities to undertake necessary action to improve the conditions of working mothers based on these results. Health professional that can maintain the balance between family and work will work more efficiently.