Background: Aged residential care (ARC) is a significant cost of dementia care. However, little is known about the predictors of ARC placement in New Zealand (NZ), which is important for service planning and funding. The aim of this study was to investigate the sociodemographic and clinical characteristics that predict future ARC placement among people who received a new diagnosis of dementia at a NZ memory service. Methods: Routinely collected baseline sociodemographic and clinical data in a memory service from 14/06/13 and 14/12/19 were linked with administrative LTC admission data up to 24/1/2020. Survival analysis was carried out using multivariate Cox regression models to determine significant risk factors and their association with ARC placement. Results: A total of 657 NZ European, Māori and Pacific Islander patients were included in the analyses. There were significant differences by ethnicity including age, living situation, comorbidity and ARC placement. Adjusted analyses showed that risk of ARC placement was increased by older age (HR 1.02 per year, 95%CI:1.00–1.05), moderate dementia (HR 1.45, 95%CI:1.05–1.99), severe dementia (HR 2.25, 95%CI:1.33–3.81), and antipsychotics (HR 1.55, 95%CI:1.04–2.32); while risk was reduced in Māori (HR 0.35, 95%CI:0.18–0.68) and Pacific Islanders (HR 0.32, 95%CI:0.20–0.51). Conclusions: Despite having more severe dementia and higher comorbidity, Māori and Pacific Islanders had reduced risks of ARC placement. There is an urgent need to better understand dementia care issues and to ensure culturally safe and responsive dementia services are accessible by Māori and Pacific Islanders living in the community.