Mental health conditions, recognised as a global crisis, were further exacerbated by the COVID-19 pandemic. Access to mental health services remains limited, particularly in low-income regions. Task-sharing interventions, exemplified by Problem Management Plus (PM+), have emerged as potential solutions to bridge this treatment gap. This study presents an evaluation of the PM+ scale-up in Sub-Saharan Africa (Ethiopia and Benin) and Eastern Europe (Croatia and Bosnia and Herzegovina) as part of a mental health and psychosocial support programming including 87 adult participants. A mixed-method approach assesses the impact of the intervention. Quantitative analyses reveal significant reductions in self-reported problems, depression, anxiety and improved functioning. Qualitative data highlight four main themes: general health, family relationships, psychosocial problems and daily activities. These thematic areas demonstrate consistent improvements across clients, irrespective of the region. The findings underscore the impact of PM+ in addressing a broad spectrum of client issues, demonstrating its potential as a valuable tool for mitigating mental health challenges in diverse settings. This study contributes to the burgeoning body of evidence supporting PM+ and highlights its promise in enhancing mental health outcomes on a global scale, particularly for vulnerable populations.