Purpose <p>Many cancer survivors experience chronic cancer-related fatigue (CCRF). While most psychosocial interventions focus exclusively on cancer survivors themselves, increasing evidence suggests that involving partners may enhance and broaden the benefits of these interventions. The primary objective of this study was to assess the acceptability and potential efficacy of COMPANION, a web-based mindfulness-based cognitive therapy for couples (15–20&#xa0;weeks). Additionally, we examined the feasibility of the trial procedures.</p> Methods <p>This single-arm pilot trial included cancer survivors and their romantic partners. Participants completed questionnaires prior to starting the therapy (T0), 2 weeks after the therapy (T1), and 1 month following T1 (T2). Predefined benchmark values were used to assess the acceptability and potential efficacy of COMPANION, as well as the feasibility of the trial procedures.</p> Results <p>Forty-six couples were screened for eligibility, 33 fulfilled the inclusion criteria and 21 entered the study. Seventy-one percent of the couples completed COMPANION (<i>n</i> = 15). Most couples were satisfied with the intervention and the couples’ approach. About two-thirds of the cancer survivors showed a clinically relevant improvement in fatigue from T0 to T1. Improvement was also seen in anxiety and depressive symptoms in both members of the couples. The trial procedures were found to be feasible.</p> Conclusions <p>Based on the benchmark values, we conclude that the intervention is acceptable and potentially efficacious. A randomized controlled trial is therefore warranted to further evaluate the effectiveness of COMPANION.</p> Implications for cancer survivors <p>After further testing, the intervention may be offered more broadly and complement much-needed psychosocial interventions to help couples cope with CCRF.</p>