Purpose: The purpose of this study was to identify subgroups of sexual and gender minority (SGM) youth who are most vulnerable to tobacco use. Methods: We analyzed data from a national nonprobability sample of 11,192 SGM youth (ages 13-17). Age of cigarette initiation and current use were modeled using Cox proportional hazard and binomial regression. Sexual and gender identities were explanatory variables and the models were adjusted for ethnoracial identity and age. Results: Approximately 7% of the sample reported current smoking. Cisgender and transgender boys had higher odds of current smoking compared with cisgender and transgender girls (adjusted odds ratio [AOR] = 1.86; 95% confidence interval [CI]: 1.56-2.21). Pansexual-identified youth had higher odds of smoking (AOR = 1.33; 95% CI: 1.05-1.70) compared with gay/lesbian youth independent of gender identity. Pansexual-identified cisgender boys had the highest smoking prevalence (21.6%). Predicted probabilities were higher among transgender boys across all sexual identities, except asexual. The hazard of smoking at a younger age was greater for transgender boys compared with cisgender boys (adjusted hazard ratio [AHR] = 1.67; 95% CI: 1.43-1.94) as well as for bisexual (AHR = 1.12; 95% CI: 1.01-1.24) and pansexual (AHR = 1.17; 95% CI: 1.03-1.33) youth compared with those who identified as gay or lesbian. Conclusions: These findings suggest that transgender boys may be at higher risk for early and current cigarette use regardless of their sexual identity, whereas smoking varied more widely for youth across different sexual identities. The findings suggest that specific subgroups of SGM youth require focused attention in tobacco control research and practice.