Urban consolidation centres (UCC) have often been highlighted as a solution to reducing freight vehicle kilometres, emissions, and congestion in urban areas. However, previous studies have presented vastly different results regarding the environmental and social benefits when UCCs are implemented. Therefore, this study aims to provide an overview of research on the sustainability assessment of UCCs, to describe dominant themes, and identify why assessments differ. A systematic literature review approach employing a content analysis was used to create the overview and identify the dominant themes in the quantification of the sustainability benefits of UCCs. As a complement, a cross-case analysis was applied to compare the results and to identify underlying differences between the studies. The content analysis revealed three dominant themes, relating to: (i) modelling aspects, (ii) different UCC set-ups, and (iii) the different performance measurements applied. Furthermore, improved consolidation is often described as the largest environmental benefit of implementing UCCs but our results show that the largest benefit can be found in switching to more environmentally friendly vehicles. However, the cross-case analysis revealed difficulties in determining the benefits of implementing UCCs because the assessment of benefits differ vastly between studies. These differences can be explained by the different scope of the system and whether or not other measures were implemented alongside a UCC. This review also highlights seven important gaps in the research that can be used to guide future research, such as a lack of methodological diversity, since most studies employ mathematical modelling, as well as a lack of transparency regarding input and output data. This is a barrier when evaluating the benefits of introducing UCCs.