Vertical Greening Systems (VGS) can offer a viable means to improve the environmental conditions of dense urban areas. Although numerous studies have explored the benefits of VGS, the findings remain fragmented and inconsistent. This study aims to unify them through a comprehensive, macro-level synthesis. Drawing on a semi-systematic review of 132 studies, it analyzes VGS benefits at the urban, building and individual levels, focusing on underlying mechanisms, key influencing factors, and both qualitative and quantitative effects. Additionally, the study reviews existing monetization methods to assess financial advantages and proposes practical application recommendations. Findings highlight that among the various benefits, water management and extended wall longevity offer the highest economic benefits, followed by improvements in acoustics, aesthetic, and thermal environments. Overall, living walls generally provide greater benefits than green facades, except in supporting biodiversity. However, when accounting for costs, only direct green facades consistently yield positive net economic returns. Moreover, limited economic research exists on the heat island effect, indoor acoustics, humidity, light environment, and well-being, particularly regarding the factors affecting humidity and lighting, which require further research. Based on these findings, this study recommends prioritizing green facades for renovations, adopting living walls in new buildings when supported by policy incentives, and integrating VGS with greywater systems to maximize economic returns. Since this review clarifies the benefit mechanisms and economic valuation of VGS, it provides a foundation for future cost-benefit analyses and supports more efficient and economically sustainable VGS strategies within broader urban sustainability agendas.