OBJECTIVES: The rapid influx of patients with COVID-19 to intensive care at a rate that exceeds pre-existing staff capacity has required the rapid development of innovative redeployment and training strategies, which considered patient care and infection control. The aim of this study was to provide a detailed understanding of redeployment and training during the first year of the COVID-19 pandemic by capturing and considering the merit of the strategies enlisted and the experiences and needs of redeployed healthcare workers (HCWs). DESIGN: The review involved a systematic search of key terms related to intensive care AND training AND redeployment AND healthcare workers within nine databases (Medline, CINAHL, PsychINFO, MedRxiv, Web of Science, The Health Management Consortium database, Social Science Research Network, OpenGrey and TRIP), which took place on 16 July 2021. Analysis consisted of a synthesis of quantitative study outputs and framework-based thematic analysis of qualitative study outputs and grey literature. These results were then combined applying an interpretative synthesis. We followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses, and the review protocol was available online. RESULTS: Forty papers were analysed. These took place primarily in the UK (n=15, 37.5%) and USA (n=17, 42.5%). Themes presented in the results are redeployment: implementation strategies and learning; redeployed HCWs' experience and strategies to address their needs; redeployed HCWs' learning needs; training formats offered and training evaluations; and future redeployment and training delivery. Based on this, key principles for successful redeployment and training were proposed. CONCLUSIONS: The COVID-19 pandemic presents unique challenges to develop flexible redeployment strategies and deliver training promptly while following infection control recommendations. This review synthesises original approaches to tackle these challenges, which are relevant to inform the development of targeted and adaptative training and redeployment plans considering the needs of HCWs.