Emerging research trends are exploring the co-gasification of refinery oil with biomass in an entrained flow gasifier because of its capability to produce high-quality syngas. However, there is still insufficient significant evidence regarding co-gasification in entrained flow gasification (EFG). In this study, Bibliometrix and VOSviewer were used to analyse publication trends of co-gasification and entrained flow gasification, to provide valuable insights into this technology’s contribution to energy transition. The study examined 376 articles published between 1997 and 2024 on the Web of Science, with peak publication in 2020. Asia and Europe lead in contributions, with China and Sweden as dominant players. Despite some international collaboration, the research field remains concentrated in just a few countries. Furthermore, the limited number of publications may be due to proprietary research conducted by private companies. Entrained flow co-gasification technology has reached commercial maturity for some fossil-based applications with a high Technology Readiness Level (TRL 9), but its integration with biomass and refinery oils remains at lower TRL levels. This review presented a system-level insight by combining bibliometric analysis with critical technology review to propose an integrated technological pathway for biomass and refinery oil co-gasification in an entrained flow gasifier for sustainable fuel production.