Female Sex Workers are among those women who are significantly more vulnerable to violence. Apart from the human rights perspective, assessing the frequency of violence among sex workers is especially important because of its relation to the spread of HIV and other sexually-transmitted infections. This cross-sectional, observational study was conducted among 263 female sex workers in southern parts of Tehran and their suburban regions in 2017 where the population is considered more socially and economically vulnerable. To evaluate univariate analysis between sexual violence and physical violence as dependent variables and the assumed exposures as well as confounders, the models were built distinctly. The models included exposures of the questionnaire as independent variables. The exposure factors with a p value of less than 0.2 were moved into the multiple logistic regression models. The rates of sexual violence and physical violence were reported as 72.2% and 82.3% respectively. According to our results, sexual violence is associated with higher education, working in streets, drug usage, having the experience of forced unprotected sex and feeling of discrimination. Physical violence is associated with low education, drug usage and feeling of discrimination in multiple analyses. Addressing the violence against female sex workers is a complex multifactorial issue in Iran. It requires structural changes in some social, legal, economic and health infrastructure programs.