This study examined the association between prenatal cannabis exposure and autism spectrum disorder (ASD) diagnoses and traits. A total sample of 11,570 children (ages 1–18; 53% male; 25% Hispanic; 60% White) from 34 cohorts of the National Institutes of Health-funded environmental influences on child health outcomes consortium were included in analyses. Results from generalized linear mixed models replicated previous studies showing that associations between prenatal cannabis exposure and ASD traits in children are not significant when controlling for relevant covariates, particularly tobacco exposure. Child biological sex did not moderate the association between prenatal cannabis exposure and ASD. In a large sample and measuring ASD traits continuously, there was no evidence that prenatal cannabis exposure increases the risk for ASD. This work helps to clarify previous mixed findings by addressing concerns about statistical power and ASD measurement.