Retrofitting existing residential buildings presents a feasible approach to improving energy efficiency. Therefore, recognising the critical success factors (CSFs) for residential building energy retrofitting (BER) has remained a significant topic in this climate change era. However, given the fragmented nature of past findings, this study reviewed past studies on the CSFs for residential BER. Utilising Arksey and O’Malley’s framework, 138 studies were initially examined, with 33 meeting the inclusion criteria and synthesised according to the PRISMA-ScR guidelines. The review started with a bibliometric analysis, including publication trends, types, geographical focus, etc., and found growing interest in this topic amongst authors in China, Germany, Saudi Arabia, the UK, and Europe. The scoping review results highlight seven overarching themes of CSFs: project-, contract-, stakeholder-, team-, financial-, regulation-, and material/technology-related. Notably, the most emphasised across the studies were stakeholder-, project-, regulation-, and financial-related CSFs. A further review of the included studies revealed that the dominant methods used in past studies were factor analysis, regression analysis, social network analysis (SNA), and structural equation modelling (SEM). This study provides valuable insights for regulatory bodies, construction professionals, project managers, and homeowners seeking to develop customised retrofitting solutions, advancing residential BER research and practice. Further research is suggested to understand how combinations of factors can drive retrofitting success across varied contexts.