This paper investigates changes in relativization in Singapore English broadsheet newspapers from 1993 to 2016. One of the first diachronic studies in Singapore English (SgE), it also explores corresponding data from the diachronic Siena-Bologna (SiBol) news corpus. As SgE is in the endonormative stabilization phase in Schneider's (2007) Dynamic Model of postcolonial Englishes, divergence from British English (BrE) is to be expected. In this study, the dataset is a new Singapore English Newspaper (SEN) corpus compiled from local news articles in 1993, 2005 and 2016, and the corpus tool employed is Sketch Engine. The results reveal changes in relativization practices in SEN over the given period, many of which occur in a similar pattern as those identified in SiBol, albeit at varying rates of change. Most significant of these include a sharp decline in the which relativizer in restrictive relative clauses with non-animate antecedents, complemented by a rise in that. The change has been so rapid that although which relative clauses were more common than that clauses in 1993, that has subsequently overtaken which for both the corpora. One shift in SEN that is different from SiBol is the increase in frequency of non-restrictive relative clauses in SgE. The likely motivators for the changes in the two varieties are identified as colloquialization, densification and prescriptivism. The effect each of these factors could have had on the varieties are discussed, as well as the implications that the findings have on our understanding of the evolutionary status of SgE as a postcolonial variety.