Previous studies supported the association between insomnia symptoms and suicidal ideation in patients with mental or psychological diseases. This study aimed to examine the associations between insomnia symptoms, general self-efficacy, and suicidal ideation among community-based adult population. Standardized questionnaire was distributed to 2051 community-dwelling adults in Lishui district of Jiangsu Province in China, to assess their socio-demographics, insomnia symptoms, general self-efficacy, and suicidal ideation. Multiple binary logistic regression or linear regression and mediation analysis with bootstrap resampling method were performed. Results showed that the weighted prevalence of lifetime suicidal ideation was 6.38%. Insomnia symptom was associated with higher odds of suicidal ideation after adjusting for sociodemographics and mental health status (odds ratio [OR] = 2.85, 95% confidence interval [CI] [1.66, 4.89]), and the OR of insomnia symptom with suicidal ideation decreased but remained significant after additionally adjusting for general self-efficacy (OR = 2.62, 95% CI [1.52, 4.53]). Participants with insomnia symptom were also significantly associated with lower general self-efficacy (β = −0.96; 95% CI [−1.70, −0.21]), whereas higher general self-efficacy was associated with a lower odds of suicidal ideation (OR = 0.92, 95% CI [0.87, 0.99]). In conclusion, general self-efficacy was associated with both insomnia symptom and suicidal ideation among the community-dwelling adult population.