Background Although psychoeducation programmes are the gold-standard intervention in bipolar disorder (BD), more innovative tools are needed to broaden and consolidate their effects, especially on treatment adherence. Serious games could be an option. Methods We carried out a two-arm open randomized controlled trial to compare the add-on use of the serious game BIPOLIFE® for one month (n = 20) vs. treatment as usual (TAU; n = 21) following the completion of a psychoeducation programme in euthymic adults with BD. The primary outcome was the percentage of adherent patients (i.e., patients with a Medication Adherence Rating Scale, MARS, total score >7) at 4 months after the end of the psychoeducation programme. We also measured the changes in therapeutic adherence and beliefs on pharmacological treatments (Drug Attitude Inventory, DAI) between study inclusion and the 1-month (end of BIPOLIFE® use) and 4-month visits, healthcare use during the study period, and BIPOLIFE® acceptability. Results The percentage of adherent patients was lower in the BIPOLIFE® group than in the TAU group at inclusion (p = 0.02). Conversely, the absolute variation of the MARS and DAI scores was higher in the BIPOLIFE® than in the TAU group at the 1-month visit (p = 0.03 and p = 0.002, respectively) but not at the 4-month visit (p = 0.22 and p = 0.07, respectively). Limitations Small sample size, and low frequency of connexion to BIPOLIFE® declared by the patients. Conclusion BIPOLIFE® may help patients with BD to increase their confidence in medications, if used regularly.