Background Within the integrated motivational-volitional model of suicidal behavior, entrapment that consecutively leads to hopelessness is considered as a proximal risk factor for suicidal ideation. Entrapment can refer to both external and internal circumstances whereby results of recent studies indicate that internal entrapment plays a more important role than external entrapment in the development of suicidal ideation. It has been considered that to escape internal entrapment might be more complicated than to change external circumstances. However, it remains unclear whether the greater effect of internal entrapment on suicidal ideation is due to greater feelings of hopelessness. Therefore, the aim of this study was to address this research gap and to examine the effects of internal and external entrapment on hopelessness and suicidal ideation. Methods N = 454 participants from a community sample (75% female) aged between 18 and 73 years (M = 29.91, SD = 11.56) conducted a cross-sectional online survey. All participants were assessed for suicidal ideation, hopelessness, and internal as well as external entrapment. Pearson product-moment correlations and two mediation analyses were conducted. Results All constructs were significantly correlated. For both internal and external entrapment, an effect on suicidal ideation was found. Both effects were partially mediated by hopelessness, this mediation was larger for external entrapment. The completely standardized indirect effect used to compare the mediation models was larger for external entrapment than for internal entrapment. Conclusions Hopelessness mediated the association between external entrapment as well as internal entrapment and suicidal ideation. This effect was larger for external entrapment.