To evaluate smoking history and change in smoking behavior, from 1 year before through 7 years after Roux-en-Y gastric bypass (RYGB) surgery, and to identify risk factors for post-surgery smoking. Smoking behavior in the context of bariatric surgery is poorly described. Adults undergoing RYGB surgery entered a prospective cohort study between 2006 and 2009 and were followed up to 7 years until ≤2015. Participants (N = 1770; 80% female, median age 45 years, median body mass index 47 kg/m2) self-reported smoking history pre-surgery, and current smoking behavior annually. Almost half of participants (45.2%) reported a pre-surgery history of smoking. Modeled prevalence of current smoking decreased in the year before surgery from 13.7% [95% confidence interval (CI) = 12.1-15.4] to 2.2% (95% CI = 1.5-2.9) at surgery, then increased to 9.6% (95% CI = 8.1-11.2) 1-year post-surgery and continued to increase to 14.0% (95% CI = 11.8-16.0) 7-years post-surgery. Among smokers, mean packs/day was 0.60 (95% CI = 0.44-0.77) at surgery, 0.70 (95% CI = 0.62-0.78) 1-year post-surgery and 0.77 (95% CI = 0.68-0.88) 7-years post-surgery. At 7-years, smoking was reported by 61.7% (95% CI = 51.9-70.8) of participants who smoked 1-year pre-surgery (n = 221), 12.3% (95% CI = 8.5-15.7) of participants who formerly smoked but quit >1 year pre-surgery (n = 507), and 3.8% (95% CI = 2.1-4.9) of participants who reported no smoking history (n = 887). Along with smoking history (ie, less time since smoked), younger age, household income <$25,000, being married or living as married, and illicit drug use were independently associated with increased risk of post-surgery smoking. Although most adults who smoked 1-year before RYGB quit pre-surgery, smoking prevalence rebounded across 7-years, primarily due to relapse.