Suicide-loss survivors are an at-risk population for complicated grief and suicide ideation. This study examined mentalization deficits as a possible moderator of the association between complicated grief and suicide ideation. Suicide-loss survivors (N = 152) completed questionnaires on complicated grief, suicide ideation, and mentalization deficits. Mentalization deficits facilitated suicide ideation, beyond the contribution of complicated grief. Complicated grief and suicide ideation were more strongly associated at higher mentalization deficit levels. Limitations include the non-representative cross-sectional nature of the sample and the use of a single item for suicide ideation. The findings highlight the critical link between complicated grief and suicide ideation among suicide-loss survivors and mentalization deficits' role as its possible facilitator.