The Broad-Minded Affective Coping (BMAC) intervention is a theory-driven cognitive therapy aiming to reduce suicidal ideation through guided positive mental imagery. We explored the feasibility and acceptability of a randomised controlled trial to evaluate the BMAC intervention in university students. The trial was a two-arm, randomised (ratio 1:1) controlled feasibility trial comparing risk assessment and signposting with or without the BMAC intervention (ISRCTN 13621293; ClinicalTrials.gov NCT05296538). Participants had recent suicidal ideation or behaviour. Feasibility outcomes concerned recruitment, retention, intervention adherence, completion of a suicidal ideation assessment, and the safety of the procedures. Clinical outcomes and putative mechanisms were recorded at baseline and after eight, 16, and 24-weeks. All feasibility criteria were met. Sixty-five participants were randomized (99 % of target sample). Retention to follow-up was high at all timepoints (89–91 %). In the treatment arm, 30 out of 33 participants (91 %) attended ≥2 sessions of the BMAC. Retained participants completed a suicidal ideation assessment with no missing data. There were 19 serious adverse events, but none were related to the trial procedures or intervention. Effect estimates for suicidal ideation favoured the intervention. The trial and intervention were acceptable, feasible, and safe. The efficacy of the intervention requires evaluation in a definitive trial.