Motherhood is common among female sex workers (FSWs) and many have at least one biological child. Preventable mother-to-child transmission of HIV can occur given poor uptake of contraception coupled with high rates of unintended pregnancies among FSWs. Globally, there are 2.1 million children living with HIV, and antiretroviral treatment coverage is dismally low at 43%. Without timely diagnosis and treatment, half of all children born with HIV will die by the age of 2 years. By integrating services for key populations and their children, prevention of mother-to-child transmission of HIV uptake among FSW mothers and early infant diagnosis can improve and therefore reduce transmission of HIV. This field note addresses the needs of FSWs and their children, and advocates for programs to develop and scale up comprehensive, integrated, stigma-free services for this vulnerable population. Sensitive, confidential, child-friendly, tailored services that protect FSWs while addressing their children are essential to saving these young lives and breaking the transmission cycle of the virus. By siloing programs that neglect children of FSWs, we are missing opportunities and existing entry points to take an innovative, holistic, family approach to care, support, and treatment services that could improve outcomes. Given the high prevalence of HIV in FSWs and other stigmatizing factors which affect access to services, children of FSWs can no longer afford to be left behind and the time is now to prioritize them in current and future HIV programming.