The market for online sexually transmitted infection (STI) services is rapidly expanding. Online health services often have unequal uptake among different demographics of the population. There is a need to understand how different online delivery options for STI testing may appeal to different groups of young people, particularly young people who have higher rates of STI diagnoses. An online survey of young Australians aged 16 to 29 years was conducted to understand service preferences regarding consultation (telehealth, fully automated questionnaire), testing (electronic pathology form, at-home self-sampling), and treatment (e-prescriptions, mailed oral tablets). Multivariable multinomial logistic regression examined associations between user characteristics and service preferences, and adjusted relative risk ratios (aRRRs) and 95% confidence intervals (CIs) are presented. Among 905 respondents, rural youth were more likely to prefer fully automated questionnaires (aRRR, 1.9; 95% CI, 1.0-3.5) over telehealth consultations, whereas culturally and linguistically diverse (CALD) youth were less likely (aRRR, 0.4; 95% CI, 0.2-0.7). Rural youth preferred at-home self-sampling kits (aRRR, 1.9; 95% CI, 1.3-2.7) over electronic forms for on-site collection at pathology centers, with the opposite for CALD youth (aRRR, 0.7; 95% CI, 0.5-1.0). Receiving oral antibiotics by mail was preferred by rural youth (aRRR, 2.3; 95% CI, 1.1-4.6) over for in-clinic treatment, but not for CALD youth (aRRR, 0.5; 95% CI, 0.4-0.8). Our findings suggest that rural youth tend to prefer self-navigated and automated options, whereas CALD prefer options with greater provider engagement. Online STI service providers should consider how different service options may affect equitable uptake across the population and implications for addressing disparities in testing and treatment.