Objective Treatment decision‐making in bipolar II disorder is complex due to limited evidence on treatment efficacy and potentially burdensome side‐effects of options. Thus, involving patients and negotiating treatment options with them is necessary to ensure that final treatment decisions balance both clinician and patient preferences. This study qualitatively explored clinician views on (a) effective treatment decision‐making, unmet patient needs for (b) decision‐support and (c) information. Method Qualitative semi‐structured interviews with 20 practising clinicians (n = 10 clinical psychologists, n = 6 general practitioners, n = 4 psychiatrists) with experience treating adult outpatients with bipolar II disorder were conducted. Interviews were audiotaped, transcribed verbatim and analysed thematically using framework methods. Self‐report professional experience, and clinician preferences for patient decision‐making involvement were also assessed. Results Qualitative analyses yielded two inter‐related themes: (a) challenges and barriers to decision‐making and (b) facilitators of clinician decision‐making. Symptom severity, negative family attitudes, system‐based factors, and information gaps were thought to pose challenges to decision‐making. By contrast, decision‐making was supported by patient information, family involvement and patient‐centredness, and a strong therapeutic relationship. Clinician views varied depending on their professional background (medical vs clinical psychologist), patient involvement preferences, and whether the clinician was a bipolar specialist. Conclusions Whilst clinicians uniformly recognise the importance of involving patients in informed treatment decision‐making, active patient participation is hampered by unmet informational and decision‐support needs. Current findings inform a number of bipolar II disorder‐specific, clinician‐endorsed strategies for facilitating patient decision‐making, which can inform the development of targeted patient decision‐support resources for use in this setting.