Suicide is a major public health concern and leading cause of death among men in Canada. This study reports the feasibility and acceptability of Buddy Up, a peer-based suicide prevention campaign for men. A mixed-methods approach was used to analyze respondent survey questionnaires ( n = 48) and individual participant interviews ( n = 19) collected from campaign users. Survey respondents reported that they enjoyed their involvement in the campaign (92%), were more confident to talk with men about mental health and suicide (95%), and would recommend Buddy Up to others (95%). Qualitative interviews were thematically analyzed to develop three inductively derived themes: (a) Engaging men with relatable masculine content and design: “Buddy Up really spoke to them in their language,” highlighting the importance of understanding and working with gendered practices and motivations to legitimize and motivate involvement in suicide prevention; (b) Leveraging campaign participation to initiate conversations and promote mental health: “It gives men language and license to start asking questions,” revealing ways in which participants utilized Buddy Up to negotiate and norm checking-in to promote men’s mental health; and (c) Driving new masculine cultures: “We start every meeting with a mental health moment,” identifying how participants fostered healthy milieus for disclosing mental health challenges with teamwork and preventive action under the banner of Buddy Up. The study findings support the feasibility of Buddy Up and highlight the acceptability of peer-based approaches to mental health promotion. The findings can also empirically guide future efforts for systematically building men’s peer-based suicide prevention programs.