We examined the association between autistic traits and sexual orientation in a general adult population (N = 47,356). Autistic traits were measured with the ten items Autistic Quotient questionnaire using a cut-off score of ≥ 6. Sexual orientation was assessed by self-report. Multinomial logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for sexual orientation categories. Participants with autistic traits were more likely to identify as bisexual (OR 1.73; 95% CI 1.01-2.9) and to feel that their sexual orientation could neither be described as hetero-, homo- nor bisexual (OR 3.05; 95% CI 2.56-3.63), compared to individuals without autistic traits. Autistic traits are associated with minority sexual orientation, and perhaps with uncertain self-identification and/or a defiance of traditional ways of categorizing sexual identity.