Adolescent self-harm is a significant public health issue. We aimed to understand how parent stress response styles to their child’s self-harm affects their wellbeing and functioning and the wider family. Thirty-seven participants in Australia (parents; 92% female) completed a mixed methods survey regarding their adolescent child’s self-harm. We conducted Pearson zero-order correlations and independent t-tests to examine the impact of parent response style on their quality of life, health satisfaction, daily functioning, and mental health. We also used thematic analysis to identify patterns of meaning in the data. Two-thirds of participants reported mental ill health and reduced functional capacity due to their adolescent’s self-harm. Parents with a more adaptive response style to stress had better mental health. Qualitative analyses revealed parents experienced sustained feelings of distress and fear, which resulted in behavioural reactions including hypervigilance and parental mental health symptoms. In the wider family there was a change in dynamics and parents reported both functional and social impacts. There is a need to develop psychological support for the adolescent affected and parents, to support more adaptive response styles, and decrease the negative effects and facilitate the wellbeing of the family unit.