Background: Due to advances in multimodal therapies, most children survive cancer. In addition to the stresses of diagnosis and treatment, many families are now navigating the challenges of survivorship. Without sufficient support, the ongoing distress that parents experience after their child's cancer treatment can negatively impact the quality of life and psychological wellbeing of all family members. Methods/Design: The 'Cascade' (Cope, Adapt, Survive: Life after C AncEr) study is a three-arm randomised controlled trial to evaluate the feasibility and efficacy of a new intervention to improve the quality of life of parents of young cancer survivors. Cascade will be compared to a peer-support group control and a 6-month waitlist control. Parents (n = 120) whose child (under 16 years of age) has completed cancer treatment in the past 1 to 12 months will be recruited from hospitals across Australia. Those randomised to receive Cascade will participate in four, weekly, 90-minute online group sessions led live by a psychologist. Cascade involves peer discussion on cognitive-behavioural coping skills, including behavioural activation, thought challenging, mindfulness and acceptance, communication and assertiveness skills training, problem-solving and goal-setting. Participants randomised to peer support will receive four, weekly, 90-minute, live, sessions of non-directive peer support. Participants will complete measures at baseline, directly post-intervention, one month post-intervention, and 6 months post-intervention. The primary outcome will be parents' quality of life. Secondary outcomes include parent depression, anxiety, parenting self-agency, and the quality of life of children in the family. The child cancer survivor and all siblings aged 7 to 15 years will be invited to complete self-report quality of life measures covering physical, emotional, social and school-related domains. Discussion: This article reviews the empirical rationale for group-based, online cognitive-behavioural therapy in parents of children who have recently finished cancer treatment. The potential challenges of delivering skills-based programs online are highlighted. Cascade's videoconferencing technology has the potential to address the geographic and psychological isolation of families after cancer treatment. Teaching parents coping skills as they resume their normal lives after their child's cancer may see long-term benefits for the quality of life of the family as a whole. Trial registration: ACTRN12613000270718 (registered 6 March 2013).