Children in families with mental health problems may encounter multiple risks to their well-being. General aims of peer support programmes for these children include fostering resilience and effective coping strategies, and enhancing self-esteem and social skills. This study aimed to evaluate outcomes from a pilot multi-site implementation of the ON FIRE peer support programme. The purpose of ON FIRE is to cultivate hope, resilience and well-being in children and adolescents aged 8-17 years living in families affected by sibling or parental mental health problems. We employed a pre-post test (baseline and 4 months) evaluation using a suite of outcome measures. The Strengths and Difficulties Questionnaire (SDQ), Children’s Hope Scale, Kids Connections Scale and Positive and Negative Affect Scale for Children (PANAS-C) were completed for 64 child/adolescent participants. At baseline, participants had significantly greater difficulties compared with Australian norms. At 4 months, there were significant differences in children’s hope and in connections outside the family. There were no significant differences in the SDQ or the PANAS-C.