Background Due to the SARS-CoV‑2 crisis, online adaptation of sleep trainings is necessary. As sleep disturbances in school children are common, prevention of chronification is essential. The aim of this study was to adapt an established age-oriented cognitive behavioral therapy for insomnia (CBT-I) group training for 5–10-year-old children with insomnia and their parents to an online version (group iCBT-I). Methods The adaptation procedure and structure of the iCBT‑I are described. To assess acceptance the Online Sleep Treatment Acceptance questionnaire (OSTA) and the Online Sleep Treatment Feedback questionnaire (OSTF) were implemented. In addition, trainers filled in the Adherence and Feasibility Questionnaire for Online Sleep Treatment (AFOST). Sleep problems were assessed using a structured interview for sleep disorders in children and clinical interview, and the Children’s Sleep Habit Questionnaire (CSHQ-DE). Emotional problems were evaluated with the Child Behavior Checklist (CBCL 4-18). Results This pilot study included 12 parents and 6 children fulfilling insomnia criteria prior to online training. The adapted online version consisted of three parental sessions, whereas child-oriented sessions were transferred into videoclips. The new group iCBT‑I was well accepted by parents. Parents scored the online version as helpful and time saving based on the OSTA and trainers estimated the adapted version to be feasible and effective. According to AFOST, adherence was given. After training, 67% of children showed reduced sleep problems according to parental rating. Conclusion Parental acceptance of a group iCBT‑I for school children and their parents was very good and parents scored the videos for their children as very helpful. Trainers declared the adapted version to be feasible. A further study with a larger sample is necessary.