Objective: Online psychological therapies provide a way to connect adolescent and young adult (AYA) cancer survivors to evidence-based support. We aimed to establish the feasibility, acceptability, and safety of Recapture life, a six-session group-based online cognitive-behavioural intervention, led by a facilitator, for AYAs in the early post-treatment period.Methods: A randomised-controlled trial compared Recapture Life to an online peer-support group control and a waitlist control. Participants could nominate a support person. Acceptability was assessed using study opt-in and retention rates, participant-reported benefits/burdens of participation, and group facilitator burden.We also assessed the feasibility (eg, frequency/impact of technological difficulties) and psychological safety (ie, occurrence of clinically concerning distress) of the program.Results: Sixty-one participants took part (45 AYAs, 51.1% female; 19 support people). The opt-in rate was 30%, the enrolment rate was 87%, and 75% of participants took part in ≥5/6 sessions. AYAs reported high benefit and low burden of participation. Overall, 95 online group sessions were conducted; few required rescheduling by group facilitators (3%), but many took place outside of office hours (~90 hours). It took 40 days on average to create online groups, but established weekly sessions commenced quickly (M = 4.0 minutes). Technological difficulties were common but had a low impact on intervention delivery. Although 54% of AYAs returned a clinically concerning distress screen at some point, none reflected acute mental health risks. Conclusions: The data largely indicate that Recapture Life is an acceptable, feasible, and safe model of evidence-based psychological support for AYAs during early survivorship, which nevertheless experienced common challenges in online/AYA intervention delivery. 28:284-292. wileyonlinelibrary.com/journal/pon KEYWORDS adolescent, feasibility, cancer, psychological interventions, oncology, online videoconferencing, survivorship, young adult AYAs High perceived benefit a post booster session / 12m-FU [N (%)] 20 (61%) / 16 (70%) 13 (59%) /12 (75%); 7 (64%) /4 (57%) Low perceived burden ‡ post booster session / 12m-FU [N (%)] 30 (91%) / 20 (87%) 20 (91%) /14 (88%); 10 (91%) /6 (86%) Support persons High perceived benefit a post booster session / 12m-FU [N (%)] 3 (25%) / 1 (11%) 1 (11%) /1 (13%); 2 (67%) /0 (0%); Low perceived burden ‡ post booster session / 12m-FU [N (%)] 12 (100%) / 9 (100%) 9 (100%) /8 (100%); 3 (100%) /1 (100%) Note: Statistics represent summary statistics across all trial arms, with the exception of homework completion. AYA = adolescent and young adult; FU = follow-up; U(x,y) = Mann-Whitney U test statistic, with n 1 = x, n 2 = y observations in each group. aComprised "quite a bit" and "very much" benefit ratings. ‡ Comprised "not at all" and "a little bit" burden ratings.