Objective To explore the effect of red and blue light combined with adapalene gel on acne severity in patients with acne vulgaris. Methods A total of 120 patients with acne vulgaris admitted to Wuhan University Hospital from September 1, 2024 to December 30, 2025 were selected, and they were divided into the reference group and the observation group by the random number table method, with 60 patients in each group. The reference group was treated with adapalene gel alone, and the observation group was treated with red and blue light combined with adapalene gel. The acne severity, aesthetic effect, clinical efficacy, adverse reaction rate and recurrence rate were compared between the two groups. Results After treatment, the GAGS score of the two groups was lower than that before treatment, and that of the observation group was lower than that of the reference group (P<0.05). After treatment, the VAS score of aesthetic effect in the two groups was higher than that before treatment, and that in the observation group was higher than that in the reference group (P<0.05). The total effective rate of the observation group (95.00%) was higher than that of the reference group (78.33%) (P<0.05). There was no signiffcant difference in the incidence of adverse reactions between the two groups (P>0.05). The recurrence rate of acne in the observation group was 8.33%, which was lower than 23.33% in the reference group (P<0.05). Conclusion Red and blue light combined with adapalene gel is effective in the treatment of acne vulgaris, with high safety and ideal aesthetic effect. It can effectively reduce acne severity and recurrence rate, which is worthy of clinical application.