Antiretroviral therapy is being rapidly scaled-up in Western Pacific region countries. Prevention and assessment of HIV drug resistance is an essential component of successful global antiretroviral therapy scale-up. We performed a systematic review of public health surveys and HIV drug resistance studies conducted in the low- and middle-income countries in the Western Pacific region. A total of 38 publications assessing HIV drug resistance were reviewed. Studies assessing transmitted drug resistance in recently infected individuals or drug resistance among individuals starting antiretroviral therapy found low rates of HIV drug resistance. Assessments of HIV drug resistance emerging in populations receiving antiretroviral therapy demonstrated variable rates of drug resistance, but suggest an urgent need to support antiretroviral therapy adherence and retention in care, ensure the use of quality assured drugs, and guarantee continuous drug supplies. Additionally, programmatic assessment informed by routine standardized surveillance of transmitted and acquired HIV drug resistance is essential to optimize antiretroviral therapy delivery in the Western Pacific region.