One of the largest threats to future development is climate change. Apparently, the building sector has been the largest source of greenhouse gas production. One prospective solution to this is "green building" that aims to provide environmentally sustainable building in terms of design, construction and maintenance. However, green buildings symbolize the next stage of buildings, and the recent growth of new green building constructions is inadequate to overcome the negative impact of existing buildings. One logical solution to reduce the environmental impact of the existing buildings is through green retrofitting. Yet there is lack of systematic review on the existing body of knowledge on green retrofitting which is critical for future research. This paper aims to critically review the existing literature on green retrofitting and to identify contemporary research trends. Additionally, with the view to the current challenges, barriers, obstacles or problems to green retrofitting, this study highlights the needs to identify the Critical Success Factors (CSFs) for successful implementation of green retrofit projects.