Objective: Adjunctive psychological interventions improve outcomes in bipolar disorder (BD), but people in latter stages likely have different clinical needs. The objective here was to test the hypothesis that for people with ≥⃒ 10 episodes of BD, a brief online mindfulness-based intervention (ORBIT 2.0) improves quality of life (QoL) relative to a Psychoeducation control. Method: A rater-masked, pragmatic superiority randomized clinical trial compared ORBIT 2.0 with active control. Both interventions were 5-week coach-supported programs with treatment as usual continued. Inclusion criteria included age 18–65 years, confirmed diagnosis of BD, and history of ≱ 10 episodes. Measures were collected at baseline, postintervention, and 3 and 6-month follow-ups. The main outcome was QoL, measured on the Brief Quality of Life in Bipolar Disorder (Brief QoL.BD) at 5 weeks, using intentiont treat analyses. Results: Among N = 302 randomized participants, the primary hypothesis was not supported (Treatment × Time β = −0.69, 95% CI [−2.69, 1.31], p =.50). The main effect of Time was not significant in either condition, indicating no improvement in either group. Recruitment was feasible, the platform was safe, both interventions were highly acceptable, but usage was suboptimal. Post hoc analyses found both interventions effective for participants not in remission from depression at baseline.Conclusions: In people with late-stage BD, an online mindfulness-based intervention was not superior to psychoeducational control in improving QoL. Online delivery was found to be safe and acceptable.Future interventions may need to be higher intensity, address engagement challenges, and target more symptomatic individuals