Lesbian, gay, bisexual, and transgender (LGBT) youth experience multiple sexual health inequities driven, in part, by deficits in parental and peer support, school-based sex education programs, and community services. Research suggests that the Internet may be an important resource in the development of sexual health among LGBT youth. We examined the feasibility of recruiting youth in same-sex relationships into an online sexual health intervention, evaluated intervention acceptability, and obtained initial estimates of intervention efficacy. LGBT youth (16 to 20 years old) completed Queer Sex Ed (QSE), an online, multimedia sexual health intervention consisting of five modules. The final sample (N = 202) completed the pretest, intervention, and posttest assessments. The primary study outcomes were sexual orientation identity and self-acceptance (e.g., coming-out self-efficacy), sexual health knowledge (e.g., sexual functioning), relationship variables (e.g., communication skills), and safer sex (e.g., sexual assertiveness). Analyses indicated that 15 of the 17 outcomes were found to be significant (p < .05). Effect sizes ranged from small for sexual orientation (e.g., internalized homophobia) and relationship variables (e.g., communication skills) to moderate for safer sex (e.g., contraceptive knowledge) outcomes. This study demonstrated the feasibility, acceptability, and initial efficacy of QSE, an innovative online comprehensive sexual health program for LGBT youth.