Human Immunodeficiency Virus (HIV) can be transferred during pregnancy from the infected mother to the fetus through the placenta or to her infant during delivery or breastfeeding. Objective: To evaluate awareness and understanding of HIV transmission and prevention from mother to child among female sex workers having and expecting pregnancy. Methods: It is a cross-sectional survey conducted in three cities: Lahore, Faisalabad and Islamabad, Pakistan. A sample size of 150 was considered as per convenience and collected using the snowball sampling technique. The data was collected using a specially designed questionnaire which was pilot tested by 10 health experts. The female sex workers of fertile age group 15-49 years who were pregnant or expecting pregnancy in the future were included. The female sex worker who was infertile or was on birth control was excluded from the study. Data were analysed with the help of the SPSS version 22. Results: The minimum and maximum age of female sex workers was 15 and 49 years respectively, with a mean age of 31.7±7.76 years. The female sex workers responded that 63(42%) know the mother-to-child transmission while the majority 87(58%) do not know that HIV infected mothers can transmit HIV to their children. The responses regarding mother-to-child transmission show that 61(21.3%) know about the trans-placental route, 100(35%) vaginal delivery, 58(20.3%) cesarean section, and 25(8.7%) breastfeeding. The response regarding the prevention of HIV from mother to a child shows that only 59(25.8%) prefer cesarean section, 29(12.7%) prefer no breastfeeding and very few 21(9.2%) prefer the use of antiretroviral therapies among infected women and children. Conclusions: In conclusion, the female sex workers were unaware of the prevention of HIV from breastfeeding and vaginal delivery. Moreover, they were unaware of precautions such as cesarean section and the usage of anti-retroviral therapies for infected mothers before delivery.