Residents of Puerto Rico face a high burden of food insecurity (FI), which has been associated with insomnia symptoms (IS). However, this association remains understudied in Puerto Rican young adults, a vulnerable group experiencing an elevated prevalence of FI and poor sleep. We evaluated the association between FI and IS and the mediating role of psychological distress symptoms among young adults in Puerto Rico. Data are derived from the PR-OUTLOOK cohort (2020-2023) of adults aged 18-29 y. We assessed FI with the six-item USDA Household Food Security Scale and IS with the 5-item Women's Health Initiative Insomnia Rating Scale. Psychological distress symptoms included depressive symptoms (CES-D-10), anxiety (STAI-10), and perceived stress (PSS-4). Poisson's regression models estimated prevalence ratios (PRs) with 95% confidence intervals (CIs). The Karlson-Holm-Breen method estimated the mediation percentage of each psychological distress symptom on the association between FI and IS. Notably, 24.8% of participants experienced FI, and 30.4% reported elevated IS. FI was associated with IS (PR = 1.41, 95% CI = 1.24, 1.60), an association partially mediated by depressive (31.6%), perceived stress (17.6%), and anxiety symptoms (17.2%), accounting for 35.8% of the mediation percentage. Future research should confirm these findings using objective assessments of sleep and psychosocial stress.