Objectives: To evaluate the efficacy and safety of lurasidone in the treatment of children and adolescents with bipolar depression presenting with mixed (subsyndromal hypomanic) features. Methods: Patients, 10-17 years of age, with a Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5), diagnosis of bipolar I depression were randomized to 6 weeks of double-blind treatment with once-daily flexible doses of lurasidone 20-80 mg or placebo. The presence of mixed (subsyndromal hypomanic) features in this pediatric bipolar depression trial was defined as a Young Mania Rating Scale score of 5 or greater at study baseline. Key efficacy measures included change from baseline to week 6 in the Childrens Depression Rating Scale-Revised (CDRS-R) score (primary endpoint) and Clinical Global Impressions-Bipolar Severity (CGI-BP-S) score, using a mixed model for repeated measures analysis. Results: At baseline, subsyndromal hypomanic features were present in 54.2% of patients. Treatment with lurasidone (vs. placebo) was associated with significantly greater reductions in CDRS-R scores at week 6, independent of the presence (-21.5 vs. -15.9, p < 0.01; effect size d = 0.43) or absence (-20.5 vs. -14.9, p < 0.01; d = 0.44) of subsyndromal hypomanic features. Likewise, lurasidone (vs. placebo) was associated with significantly greater reductions in CGI-BP-S scores at week 6, independent of the presence (-1.6 vs. -1.1, p < 0.001, d = 0.51) or absence (-1.3 vs. -1.0, p = 0.05; d = 0.31) of these subsyndromal hypomanic features. Rates of protocol-defined treatment-emergent hypomania or mania were similar for lurasidone and placebo in patients with (lurasidone 8.2% vs. placebo 9.0%) or without subsyndromal hypomanic features (lurasidone 1.3% vs. placebo 3.7%). Conclusions: In this post hoc analysis of a randomized placebo-controlled trial, lurasidone was found to be efficacious in the treatment of child and adolescent patients with bipolar depression who presented with mixed (subsyndromal hypomanic) features. No differences in safety profile, including the risk of treatment-emergent mania, were observed in patients with or without subsyndromal hypomanic features in this study.