BACKGROUND: Female sex workers (FSWs) have a 26 times greater chance of HIV infection compared to the women in the general population. The World Health Organization recommends pre-exposure prophylaxis (PrEP) for population groups with an HIV incidence of 3% or higher and FSWs in southern Africa fit this criteria. This study sought to understand factors that motivate FSWs to initiate PrEP, in Harare, Zimbabwe. METHODS: We purposively selected and recruited 20 FSWs to participate in the study in-order to gain an in-depth understanding of factors that motivate FSWs to initiate PrEP in Harare, Zimbabwe. We identified FSW who had been initiated on PrEP at a specialized clinic providing comprehensive sexual reproductive health (SRH) services for sex workers including HIV prevention options. We used a descriptive phenomenological approach to collect and analyze the data. Data was analyzed using Colaizzi's seven steps to analyze data. FINDINGS: Two broad themes were identified as intrinsic and extrinsic motivators. The two broad themes each have several sub-themes. The sub-themes under intrinsic motivation were (i) Self- protection from HIV infection and (ii) condoms bursting. Six sub-themes were identified as external motivators for initiating PrEP, these included (i) occupational risk associated with sex work, (ii) increased chance of offering unprotected sex as a motivator to initiate PrEP, (iii) positive encouragement from others (iv) need to take care of the children and (v) prior participation in HIV prevention research studies and (vi) Gender Based Violence. CONCLUSIONS: Understanding the factors that motivate FSWs to initiate PrEP is critical in developing contextually appropriate strategies to promote PrEP initiation and adherence strategies within specific and eligible populations for receiving PrEP according to the WHO guidelines (2015).