Aim: The present study was done to assess and compare the antimicrobial efficacy of ozonated olive oil and gingelly oil as subgingival irrigants adjunct to scaling and root planing by comparing the colony-forming units (CFU) of Porphyromonas gingivalis at baseline and 7 days postoperatively. Materials and methods: It was a split-mouth study design. A total of 10 chronic periodontitis patients (20 sites) with periodontal probing depths of 5–6 mm in two different quadrants were included in the present study. They were divided into two groups: group I—scaling and root planing irrigated with gingelly oil; group II—scaling and root planing irrigated with ozonated olive oil. Subgingival plaque samples were collected for assessing the microbial count of P. gingivalis by CFU/mL. The samples were collected before and 7 days after nonsurgical periodontal therapy. Results: The data were statistically analyzed by independent t-test for intergroup comparison and paired t-test for intragroup comparison. The microbial count of P. gingivalis had a statistically significant reduction in group II compared to group I. Conclusion: Ozone oil is an effective subgingival irrigant as an adjunct to scaling and root planing compared to gingelly oil. © 2024 Elsevier B.V., All rights reserved.