Suicidal ideation is a key mental health concern and a strong predictor of suicide attempts. While loneliness is a well-established correlate of suicidal ideation, few studies have explored how this association varies across sociocultural groups, especially among migrants. The study examines the relationship between migrant status, loneliness, and suicidal ideation among adults aged 18-64 residing in the provinces of Barcelona and Madrid. Specifically, it investigates: (1) whether Latin American immigrants report higher loneliness than native-born Spaniards; (2) whether immigrant status is linked to increased suicidal ideation; and (3) whether the association between loneliness and suicidal ideation differs by migration status. Data were drawn from the 2019 'Edad con Salud' cohort, comprising 1724 participants born either in Spain or Latin America. Suicidal ideation and major depressive disorder were assessed using the CIDI 3.0, while loneliness was measured with the 3-item UCLA Loneliness Scale. Ordered and binary logistic regression models were used to estimate associations, including interaction effects between loneliness and migration status. Latin American immigrants reported significantly higher levels of loneliness but not higher rates of suicidal ideation. Loneliness was associated with suicidal ideation only among native-born Spaniards. Depression and poor self-rated health were strong predictors of suicidal ideation across the full sample. The mental health impact of loneliness appears to be moderated by sociocultural context. Among Latin American immigrants, factors such as familism and the healthy migrant effect may protect against the psychological consequences of loneliness, despite its higher prevalence.