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) 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 in the previous week with little variability by age. 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 and current programs are not reaching them.