Background Social media is increasingly being used by young people for health-related issues, including communicating about suicide. Due to the concerns about causing distress or inducing suicidal thoughts or behaviors, to date young people neither have been engaged in the development of social media–based suicide prevention interventions nor have interventions focused on educating young people about safe ways to communicate about suicide online. Given the potential that social media holds to deliver messages to vast numbers of people across space and time and the fact that young people often prefer to seek help from their friends and peers, safely educating and engaging young people to develop suicide prevention messages that can be delivered via social media is an obvious next step. Objectives The objectives of this study were to (1) provide education to a small number of secondary school students about safe ways to communicate about suicide via social media; (2) engage the same young people in the development of a suite of social media–based suicide prevention multimedia messages; (3) assess the impact of this on participants; and (4) assess the acceptability and safety of the messages developed. Methods This study involved two phases. In phase 1, 20 participants recruited from two schools took part in an 8- to 10-week program during which they were provided with psychoeducation about mental health and suicide, including how to talk safely about suicide online, and they were then supported to design and develop their own media messages. These participants completed an evaluation questionnaire at the conclusion of the program. In phase 2, a larger group of participants (n=69), recruited via an opt-in process, viewed the media messages and completed a short questionnaire about each one. Results Participants in phase 1 enjoyed the program and reported that they learned new skills, such as how to talk safely about suicide online, and felt more able to provide emotional support to others (16/20, 80%). No participants reported that the program made them feel suicidal. Participants in phase 2 generally rated the media messages as safe and acceptable, although some messages were rated more highly than others. Conclusions This study suggests that young people can be safely engaged in developing suicide prevention messages, which can be disseminated via social media. Engaging young people in this process may improve the traction that such campaigns will have with other young people. The study also suggests that educating young people regarding how to talk safely about suicide online has multiple benefits and is not associated with distress. Overall, these findings pave the way for new approaches to prevent suicide among young people.