Background: Stigmatizing attitudes toward mental illness and low mental health literacy have been identified as links to social adversity, and barriers to seeking and adhering to treatment among adolescents suffering from mental illness. Prior research has found that it is possible to improve these outcomes using school-based mental health awareness interventions. The purpose of this study was to review empirical literature pertaining to universal mental health awareness interventions aiming to improve mental health related outcomes among students enrolled in US K12 schools, especially minorities vulnerable to health disparities. Methods: PsycINFO, Cochrane Library, PUBMED, and reference lists of relevant articles were searched for K-12 school-based mental health awareness interventions in the United States. Universal studies that measured knowledge, attitudes, and/or help-seeking pertinent to mental health were included. Results: A total of 15 studies were selected to be part of the review. There were 7 pretest/post-test case series, 5 nonrandomized experimental trial, 1 Solomon 4-groups, and 2 randomized controlled trial (RCT) designs. Nine studies measuring knowledge, 8 studies measuring attitudes, and 4 studies measuring help-seeking, indicated statistically significant improvements. Conclusions: Although results of all studies indicated some level of improvement, more research on implementation of universal school-based mental health awareness programs is needed using RCT study designs, and long-term follow-up implementation.