Objective: The objective of this study was to investigate the current state of insomnia among secondary vocational school students, identify its influencing factors, and explore potential mechanisms of action. Methods: The study population consisted of 2150 students (968 male and 1182 female) enrolled in a secondary vocational school in Wuhan, China. A cross-sectional research design was employed to analyze the data using descriptive statistics, correlation analysis, structural equation modeling, and bootstrapping. Results: Adolescents with poorer family functioning, higher levels of paranoid personality traits, and higher levels of anxiety are more likely to experience insomnia. There was a significant direct association between family functioning and insomnia (β = −0.153, p < 0.001). Paranoid personality traits and anxiety were not only significant independent mediators in the relationship between family functioning and insomnia (paranoid personality traits: β = 0.021, 95% CI: [−0.035, −0.008]; anxiety: β= 0.173, 95% CI: [−0.204, −0.114]) but also chain mediators (β = 0.059, 95% CI: [−0.073, −0.048]). Conclusions: Managing insomnia in secondary vocational school students requires familial and individual strategies, including reducing family conflict, improving family functioning, and addressing cognitive biases and anxiety.