Insomnia symptoms are associated with smoking and may interfere with smoking cessation. Specifically, studies have shown that smoking-related sleep problems are associated with long-term smoking relapse, and longer sleep duration is associated with successful smoking cessation. However, it is currently unclear whether pre- or post-quit insomnia symptoms are associated with smoking cessation outcomes. As such, the current study aimed to extend previous findings by using a measure of insomnia symptoms as a predictor of smoking cessation failure by Month 3 following smoking cessation treatment. Additionally, we examined whether post-quit insomnia symptoms predicted cessation outcomes. Results indicated that pre-, but not post-quit insomnia, predicted smoking cessation failure by 3-month post-cessation, after covarying for depressive symptoms, anxiety sensitivity, alcohol use disorder severity, treatment condition, and number of cigarettes per day. These findings add to the literature on insomnia symptoms as a risk factor for difficulties with smoking cessation, and suggest it may be a worthy clinical target for smoking populations who are interested in quitting smoking.