Increased demand for sexual health services (including prevention and treatment) have spurred the development of digital STI/HIV services. Earlier advances in testing technologies opened the door for self-testing and self-sampling approaches, in line with broader self-care strategies. Advances in HIV management mean that many people are living well with HIV and no longer need intensive in-person monitoring, whereas those at-risk of HIV are recommended to have regular asymptomatic STI screening and pre-exposure prophylaxis. This narrative review examines the evidence and implications of digital STI/HIV services, focused on promoting testing, facilitating testing, clinical management and referrals, partner services, and prevention. We have used a prevention and care continuum to structure the review to increase utility to policy as well as practice. Digital STI/HIV services can be interwoven into existing clinical pathways to enhance face-to-face services or standalone digital STI/HIV services. A growing evidence base, including randomised controlled trials and observational studies, should help inform strategies for designing effective digital STI/HIV services. However, most studies to date have focused on high-income countries and people with smartphones, despite a substantial burden of STI/HIV in low- and middle-income countries. There are also important differences between digital STI and HIV services that require careful consideration. We discuss digital STI/HIV service evidence and implications to inform research and programs in this exciting field.