Background: Few studies have investigated the prevalence of smoking among young people with/without intellectual disability. To date, no study has investigated the prevalence of vaping among young people with/without intellectual disability. Methods: Secondary analysis of data collected on 11 726 adolescents at age 14 years (2015) and from 9528 adolescents at age 17 years (2018) in the UK's Millennium Cohort Study. Results: The prevalence of smoking at ages 14 and 17 and of vaping at age 14 was similar among adolescents with and without intellectual disability. There was some evidence to suggest that at age 17, the prevalence of more frequent vaping was higher among girls with intellectual disability than among their female peers (5.2% vs. 1.6%, P < 0.05). Conclusions: Further large‐scale population‐based research is required to determine the prevalence of smoking and vaping among people with intellectual disability. Evidence that at age 17, the prevalence of vaping was higher among girls with potential intellectual disability than among their female peers also warrants further investigation given the increasing evidence on the potential harm to health and well‐being associated with vaping.