Previously used to refer to generic antecedents and antecedents of unknown gender, singular they has been found to increasingly occur with definite antecedents of known gender. This shift is associated with rising awareness of nonbinary gender identities and the expansion of they as a preferred pronoun. Usage of singular they has been previously examined only within Inner Circle Englishes (e.g., US English). In this study, we investigate sociolinguistic factors that influence the acceptability of singular they in Singapore English, an Outer Circle variety that is pivoting towards internal linguistic norms but also experiences frequent contact with non-local Englishes. We find that singular they is rated as significantly more grammatical by younger respondents; its rating is also constrained by definiteness and interactions between social factors, including gender and religiosity. These factors are found to be stronger predictors of singular they acceptability than linguistic prescriptivism. The diffusion of singular they to Singapore English illustrates the ongoing role of non-local contact in the evolution of this variety.