BackgroundAnxiety‐related functional impairment, as reflected by life interference, is a lesser explored but highly relevant treatment outcome, and it is crucial that it be included and examined in the evaluation of treatment outcomes of internet‐delivered Cognitive Behavioural Therapy (iCBT).MethodsThis single group, pre‐post study examined changes in life interference and anxiety symptoms in a sample of children (n = 1198; mean age 9.66 years) and adolescents (n = 721; mean age 13.66 years) participating in the BRAVE Self‐Help program in Australia.ResultsResults demonstrated that both children and adolescents showed improvements in anxiety symptoms, with effect sizes ranging from ηp2 = .194–.318. Reductions in life interference were evident for children (ηp2 = .008–.044), particularly later in the programme, but adolescents did not show such effects. Adolescents in the low completer group (completing 3–5 sessions) showed increases in at‐home interference (ηp2 = .038).ConclusionsAdolescents in particular may require more sessions before entrenched life interference, such as that resulting from avoidance behaviours, can be overcome.