Delayed Ettringite Formation is a key internal swelling reaction affecting massive or heat-cured concrete elements, with potentially severe long-term consequences on the durability of critical infrastructures and facilities. Although numerous studies, case histories and guidelines have been published over the last decade, the DEF literature remains fragmented, and no systematic mapping of this research field is currently available. This paper presents a bibliometric review of DEF in critical concrete structures over the period 2015–2025. A total of 149 articles indexed in Scopus were analysed using the bibliometrix/Biblioshiny package and VOSviewer. Performance analysis shows a steady annual growth rate of 9.6%, with most contributions published in a compact core of high-impact journals such as Construction and Building Materials and Cement and Concrete Composites. The geographical analysis highlights the leadership of France, China and Japan, reflecting their large stocks of critical concrete assets. Keyword co-occurrence and trend analyses reveal a thematic evolution from studies on experimental mechanical properties towards more focused work on non-destructive examination and damage detection in DEF-affected structures. On this basis, the paper identifies empirical, methodological and theoretical gaps, and outlines research priorities related to long-term monitoring, multi-mechanism interactions and performance-based assessment of DEF risk. The review also discusses how these insights can support engineers, designers, asset owners and industry professionals in managing DEF in critical concrete structures.