<p>Insomnia frequently co-occurs with depressive and anxiety symptoms. We examined its prevalence and sociodemographic, lifestyle, health, depressive, and anxiety correlates among adults in Zhuhai, China. Data were from 5647 adults in the 2021 Zhuhai City Residents’ Mental Health Survey. Insomnia symptoms were defined as ISI ≥ 8; clinically relevant depressive and anxiety symptoms as PHQ-9 and GAD-7 scores ≥ 10, respectively. Analyses accounted for the multistage survey design and post-stratification weights. The survey-weighted prevalence of insomnia symptoms was 14.2%. In separate fully adjusted models, the OR was 17.57 (95% CI, 9.92 to 31.10) for PHQ-9 ≥ 10 and 12.64 (95% CI, 6.56 to 24.39) for GAD-7 ≥ 10. Female sex, college education or above, underweight, meal frequencies other than three meals per day, and chronic disease were associated with higher odds of insomnia symptoms, whereas higher household income was associated with lower odds. Among 749 participants with insomnia symptoms, younger age and chronic disease were consistent correlates of greater depressive and anxiety symptom severity. These findings support attention to co-occurring mental health symptoms and further longitudinal research.</p>