--- - |2+ Abstract Objective This study evaluated a three‐session acceptance‐based cognitive‐behavioral intervention (CBT‐ACT) targeting a common symptom cluster in advanced cancer – worry‐insomnia‐depression‐fatigue. Methods Twenty‐eight patients with advanced cancers were randomly assigned to the CBT‐ACT intervention or waitlist. At pre‐intervention, participants completed a psycho‐diagnostic interview, standardized questionnaires, and a sleep diary. Intervention and waitlist groups were re‐assessed after six weeks, at which point the waitlist group completed the intervention. Results Participants receiving the intervention demonstrated improved sleep efficiency (p = 0.0062, d = 1.08), sleep latency (p = 0.028, d = ‐0.86), insomnia severity (p = 0.0047, d = ‐1.18), and worry (p = 0.026, d = 0.89) compared to waitlist controls. They also demonstrated a 7‐point reduction on depression (p = 0.03, d = ‐0.88), reduced hyperarousal (p = 0.005, d = ‐1.51), and a decrease in distress (p = 0.032, d = ‐0.83). Effects were maintained for the whole sample in sensitivity analyses. Effects on uncertainty intolerance approached significance (p = 0.058). No effect was found on fatigue. Conclusions The CBT‐ACT group performed significantly better than the waitlist control group. CBT‐ACT yielded strong effects for worry, sleep, depression, emotional distress, total distress, and hyperarousal. Future studies will enhance the fatigue and uncertainty tolerance components of the intervention. - Psycho-Oncology, Volume 0, Issue ja, -Not available-.