Optimising knowledge mobilisation in low- and middle-income countries (LMICs) could prove beneficial for improving mental health care, alleviating the global burden of high prevalence mental health problems and reducing inequalities. This review aimed to systematically review and synthesise the evidence on knowledge mobilisation for mental health improvement in LMICs, identifying barriers and facilitators and recommendations to guide progress. Four electronic databases were searched from inception to March 2024 using free text syntax combining synonyms of knowledge mobilisation, mental health and LMICs. Articles were eligible for inclusion if they were peer reviewed, on the topic of mental health and included evaluation data on knowledge mobilisation undertaken in LMICs. Included studies were quality assessed using the mixed-methods appraisal tool, and data extracted and synthesised narratively, complemented with the use of the framework for knowledge mobilisers and thematic analysis. Seventy-eight studies met the inclusion criteria. Successful knowledge mobilisation within resource-constrained settings was supported by several key facilitators. These include promoting community participation, engaging local stakeholders from the start and maintaining that engagement and building trust through equitable, long-term partnerships. Using structured frameworks helps guide systematic involvement, while fostering local ownership and leadership ensures sustainability and relevance. Knowledge mobilisation in low-resource settings faced several barriers, including limited logistical and financial resources, low literacy levels and a general lack of awareness about psychological interventions. A lack of mental health-specific training and language or translation difficulties further hindered efforts to effectively mobilise and implement mental health knowledge. Future knowledge mobilisation efforts could be strengthened by fostering sustained, trust-based collaborations among stakeholders and engaging policymakers early to ensure optimal alignment and buy-in. Emphasising local beliefs and attitudes is crucial, as is creating inclusive, participatory environments that encourage broad community involvement. Employing culturally responsive, community-driven frameworks can enhance relevance and impact, while rigorous evaluation of mobilisation strategies is critical to guide future research investment and resource allocation. Mobilising mental health knowledge in LMIC shares principles with mobilising other types of knowledge but differs in focus, stakeholders and challenges due to the stigma of mental health problems, its complexity, cultural sensitivity, misconceptions and resistance.