Background: Across Sub-Saharan Africa, young women who sell sex (YSW) face institutional barriers in accessing sexual health and HIV prevention programs designed for female sex workers. In 2018, Kenya developed a national framework to guide service provision for YSW aged 14 – 24 years. To help inform the implementation of the framework, we estimated the burden of vulnerabilities related to the Sustainable Development Goals (SDGs related to health and gender equality) and program contact among YSW. Methods: We used data from Transitions, a 2015 bio-behavioural cross-sectional survey of 408 YSW aged 14 – 24 years in Mombasa, Kenya. We estimated the prevalence of sexual (inconsistent condom use), structural (financial, violence), and reproductive health vulnerabilities; and characterized engagement with local HIV programs tailored to sex workers. We then compared the prevalence of vulnerabilities by age group (14 – 18 years, N=117; 19 – 24 years, N=291) and by program contact (ever contacted by local program for sex workers). Results: 47.3% reported inconsistent condom use with any partner in the previous week (no difference by age-group, p=1.00) . Structural vulnerabilities were common and did not vary by age: 83.6% did not have a regular source of income; 29.9% and 29.2% had experienced physical and sexual violence, respectively. 26.5% reported at least one pregnancy before age 18, and 18.5% used a non-reliable form of contraception with little variability by age. 25.7% were aware of at least one program, and only 13.7% of YSW had ever been contacted by a program (8.5% of those aged 14 – 18 years; and 15.8% of those aged 19 – 24 years, p=0.06). Sexual, structural, and reproductive health vulnerabilities did not vary by program contact. Conclusions: SDG-related vulnerabilities begin early in the lives of YSW who are not currently reached by programs designed for female sex workers.