Background: Parents of children and adolescents with chronic conditions have an increased risk of stress-related mental health problems, and reduced quality of life. Third wave Cognitive Behavioural Therapy (CBT) interventions have been shown to reduce stress in this parent population. Studies demonstrate that this efficacy endures when these therapies are delivered online. The aim of this systematic review is to investigate the efficacy of internet-based third wave CBT interventions for parents of children and adolescents with chronic conditions, and their potential in reducing stress for the parents. Methods/Design: This systematic review will follow the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) approach. A search of peer-reviewed journal articles published from January 1970 to December 2022 will be undertaken in the following databases: CINHAHL, EMBASE, EMCARE, MEDLINE, PsycINFO. Title and abstract screening together with data extraction will be completed by two reviewers, and will be arbitrated by a third reviewer, should there be any discrepancies. Risk of bias will be assessed using the Cochrane Risk of Bias tool. Data related to the primary outcome (i.e. reduction of stress in parents) will be extracted for analysis. Discussion: Third wave internet-based approaches show great promise in supporting parents cope with the stress/distress associated with parenting a child with a chronic condition. This protocol will guide a systematic literature review of the evidence for internet-based third wave interventions for the above parents. Registration: This systematic review was registered on on (Registration: ).