Rising burnout levels demand scalable solutions, yet trials comparing mobile health solutions remain scarce. This randomized controlled trial assessed the efficacy and underlying mechanisms of two self-guided applications: PsyPills™ and ACT Companion™ against a waitlist control condition. A sample of 113 participants was randomized into three groups. The digital interventions were self-administered over six weeks. Primary outcome measures included changes in burnout levels from baseline to post-treatment. Data analyses included repeated-measures ANOVAs with Bonferroni-corrected post-hoc comparisons, ANCOVAs adjusting for baseline scores, and regression-based bootstrapped mediation analyses using change scores. Attrition was high, with 64 participants included in the final analyses (56.6% retention); dropout was non-systematic. Both intervention groups showed significant reductions across all burnout dimensions compared to the control group. The REBT intervention demonstrated significantly greater reductions than the ACT intervention for emotional exhaustion (d = 2.53), depersonalization (d = 2.89), and reduced personal accomplishment (d = 2.53) (all p < 0.001). Although significant changes were observed in rational and irrational beliefs, mediation analyses did not support rational and irrational beliefs, psychological flexibility, or emotion regulation as significant mechanisms underlying burnout reduction. Although the interventions demonstrated significant effects, the study leaves several important questions unanswered. Most notably, the mechanisms through which burnout reductions occurred remain unclear. Given the study’s limited sample size, high attrition rate, and short follow-up period, these findings should be interpreted cautiously and warrant further investigation before firm conclusions can be drawn. Nevertheless, the present findings provide preliminary evidence that digital CBT-based interventions may represent a promising approach to reducing burnout symptoms.