Objective: To explore differences in tobacco information-seeking behaviours and perceptions between sexual minority and heterosexual (or 'straight') adults and to determine if these differences are mediated by tobacco use. Design: Cross-sectional national survey. Setting: Nationally representative probability-based surveys of adults 18 years of age or older in the US civilian non-institutionalised population. Methods: Data from respondents identifying as gay, lesbian, bisexual (LGB; n = 156) or straight (n = 4,964) in the US National Cancer Institute's Health Information National Trends Survey Food and Drug Administration cycles 1 and 2 (HINTS-FDA 2015, 2017) were analysed. We compared the responses of sexual minority and straight respondents aged 18 years and older concerning tobacco information-seeking behaviours and perceptions. Results: Sexual minority respondents were more likely than their straight counterparts to seek out tobacco health information, to look for information about e-cigarettes and to use the Internet for health information searches. Some of these differences were mediated by tobacco use. Sexual minority respondents were similar to their straight counterparts regarding perceptions of trust and confidence in tobacco health information, as well as perceptions of the hazards of tobacco use. Conclusion: Because sexual minority adults have higher rates of tobacco use and higher rates of tobacco information seeking than others, tobacco health information campaigns should consider carefully tailoring the messages directed towards sexual minority populations.