Rationale Suicidality is a major public health concern with limited treatment options. Accordingly, there is a need for innovative interventions for suicidality. Preliminary evidence indicates that treatment with the psychedelic ayahuasca may lead to decreases in depressive symptoms among individuals with major depressive disorder (MDD). However, there remains limited understanding of whether ayahuasca also leads to reductions in suicidality. Objective To examine the acute and post-acute effect of ayahuasca on suicidality among individuals with MDD. Methods We conducted a secondary analysis of an open-label trial in which individuals with recurrent MDD received a single dose of ayahuasca ( N  = 17). Suicidality was assessed at baseline; during the intervention; and 1, 7, 14, and 21 days after the intervention. Results Among individuals with suicidality at baseline ( n  = 15), there were significant acute (i.e., 40, 80, 140, and 180 min after administration) and post-acute (1, 7, 14, and 21 days after administration) decreases in suicidality following administration of ayahuasca. Post-acute effect sizes for decreases in suicidality were large (Hedges’ g  = 1.31–1.75), with the largest effect size 21 days after the intervention ( g  = 1.75). Conclusions When administered in the appropriate context, ayahuasca may lead to rapid and sustained reductions in suicidality among individuals with MDD. Randomized, double-blind studies with larger sample sizes are needed to confirm this early finding.