Background The gingivitis treatment protocols aim to stop the progression of inflammation and prevent the affliction of deeper periodontal tissues. Current research focuses on novel methods that can be applied with handheld and ultrasonic devices to increase the effectiveness of non-surgical periodontal treatment. Ozone has been shown to have a strong antimicrobial effect against bacteria that play a role in the etiology of gingival/periodontal diseases. Research evaluating the effects of ozone gas on the treatment of gingival tissues is limited. Aim We investigated the effects of ozone application during the scaling procedure on clinical parameters of gingivitis in smokers and non-smokers and to investigate the efficacy of ozone gas in periodontal treatment. Methods A total of 40 subjects, 27 males/13 females-20 smokers/20 non-smokers-with plaque-induced gingivitis, were selected. The patients underwent a single session of full-mouth supragingival and subgingival scaling. Gaseous ozone application was performed on a randomly selected maxillary quadrant. The other maxillary quadrant was designated as the control group receiving only initial periodontal treatment. Clinical parameters, such as PI, GI, GBTI, and PPD, were measured before and 1 week after treatment. Results Our study shows that ozone therapy significantly improves clinical parameters in smokers and non-smokers when applied in addition to periodontal therapy. Conclusions Additional studies comparing the effect of ozone therapy on smokers and non-smokers to the effects of oral mouthwashes may provide valuable contributions to the field.