Ultrapulse fractional CO laser is effective for acne atrophic scars. Whether this effectiveness is affected by sleep quality remains unclear. Aiming to investigate the relationship between sleep quality and postoperative effectiveness, a retrospective clinical study was conducted, enrolling 83 patients with atrophic acne scar. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI) questionnaire at 3 months after the end of the first treatment. The ECCA (échelle d'évaluation clinique des cicatrices d'acné) scale was used to evaluate the clinical effectiveness before and at 3 months after treatment. The patients were divided into a mild to moderate improvement group and a good to excellent improvement group, based on whether they achieved a 50% ECCA improvement rate. PSQI score was higher in the mild and moderate improvement group than in the good to excellent improvement group (7.6 ± 4.5 vs 3.8 ± 1.7, p < 0.001). Multivariate logistic regression showed that both PSQI score (odds ratio = 0.6 [95% CI = 0.5-0.8], p < 0.001) and scar type were correlated with postfractional CO laser effectiveness. Pearson correlation analysis suggested that PSQI score was negatively correlated with ECCA decline score (r = -0.6139, p < 0.0001). Receiver operating characteristic curve analysis showed that PSQI score (area under the curve = 0.759) and scar type (area under the curve = 0.737) were all closely correlated with postoperative effectiveness, without statistical difference between their accuracies (p = 0.647). Decision curve analysis demonstrated that both PSQI score and scar type correlated with postoperative effectiveness. Our results demonstrated that sleep quality correlates with the postoperative effectiveness of ultrapulse fractional CO laser in the treatment of atrophic acne scars.