Introduction:Research has paid limited attention to understanding factors that are associated with unmet contraceptives needs among female sex workers (FSWs). In order to fill this knowledge gap we estimated the prevalence of unmet contraceptives needs and examined factors that were associated with unmet contraceptives needs among FSWs in semi urban Blantyre, Malawi.MethodsWe used systematic sampling to recruit 290 FSWs in semi urban Blantyre between February and March 2019. In this cross sectional study, we used questionnaire interviews to collect quantitative data. We calculated the mean and standard deviation for continuous variables and proportions for categorical variables to describe the data. Logistic regression analysis was used to investigate the association between unmet needs (the outcome variable) and explanatory variables such as: having a steady partner, fear of contraceptives’ side effects and having a history of sexual transmitted infections.ResultsOut of the 290 study participants 102 (35.2%) reported unmet needs for contraceptives. The following factors were significantly associated with unmet contraceptives needs in multivariate analysis: FSWs’ history of physical and sexual violence by clients [OR 3.38, 95% CI (1.10, 10.43)], p < 0.03, participants with a steady partner [OR 3.28, 95% CI (1.89, 5.68)], p < 0.001, and participants who feared side effects of contraceptives [OR 2.99, 95% CI (1.73, 5.20)], p < 0.001.ConclusionThere is need to improve awareness of contraceptives among FSWs in semi urban Blantyre. Sexual and Reproductive Health services (SRH) should address barriers to contraceptives use such as sexual transmitted infections, clients’ violence, fear and misinformation on contraceptives. There is also a need to improve the knowledge, attitudes, and counseling skills of health providers in order to address unmet contraceptives needs among FSWS.