Approximately each year, 800,000 people die by suicide. Around the world, there has been significant investment in finding interventions that work to prevent suicide. Media campaigns are one such intervention. Suicide prevention media campaigns aim to raise awareness about suicide, change unhelpful attitudes towards suicide, reduce stigma, improve help-seeking behaviour and ultimately reduce deaths by suicide. Four electronic databases were searched for studies that examined the effectiveness of media campaigns as a means of preventing suicide. Studies were included if they reported on the effectiveness or efficacy of a suicide prevention media campaign and contained at least one suicide-related outcome such as awareness, help-seeking intentions, help-seeking behaviour (e.g., accessing treatment and calling crisis helplines) or rates of suicide. Fourteen studies evaluating 13 unique campaigns were identified. Studies were primarily conducted in Western countries, with 42% conducted in Australia. These studies were primarily conducted in real-world settings, using quasi-experimental designs and only five utilising Randomised Control Designs. Most of the media campaigns targeted audiences who might be at risk of suicide, people who might know someone at risk of suicide or the general public. Several campaigns targeted specific at-risk audiences: specifically young people, military veterans, men, police officers and farmers. Campaign messages were commonly disseminated via social media, online, videos, newspaper posters, pamphlets, radio and television. Most studies found that campaigns improved awareness and exposure to messages. Some studies found that media campaigns could boost help-seeking intentions and behaviour and reduce suicide rates, whereas others suggested that campaigns made no difference. Campaigns with greater exposure or campaigns that reinforced messages via multiple means had more significant impacts. While these results are promising, further evaluations are needed to determine the most effective message content and design, exposure level and delivery method to prevent suicide.