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.