Smoking is a risk factor for respiratory diseases, and it worsens sleep quality due to nicotine stimulation and sudden nicotine withdrawal during sleep. This can increase the severity of OSA through alterations upper airway inflammation and neuromuscular function, arousal mechanisms, and sleep architecture. Therefore, it may lead to sleep-disrupted breathing, particularly obstructive sleep apnea (OSA). Herein, this study aims to research the association between smoking and OSA through the STOP-Bang index. In this study, total sample of 3442 participants (1465 men and 1977 women) were analyzed. We used data from the Korea National Health and Nutrition Examination Survey in 2020 by classifying adults into current, ex-, and non-smokers. A multiple logistic regression analysis was used to investigate the association between smoking and OSA. Furthermore, multinomial regression analysis was used to investigate the effect of smoking cessation. For males, compared to the non-smokers, the odds ratios (OR) for the OSA were significantly higher in the ex-smokers (OR: 1.53, 95% confidence interval(CI) 1.01–2.32) and current smokers (OR: 1.79, 95% CI 1.10–2.89). In females, higher ORs were observed for OSA risk, similar to the non-smokers, smoking cessation, and pack-years. Among men, OSA was significantly associated with a moderate risk for ex-smokers (OR: 1.61, 95% CI 1.05–2.48) and a severe risk for current smokers (OR: 1.88, 95% CI 1.07–3.29). This study observed that smoking might contribute to OSA risk among adults. Smoking cessation can help to manage sleep quality properly.