The management of chronic non-cancer pain (CNCP) with Chronic Opioid Therapy (COT) is controversial. There is a lack of consensus on how COT is defined resulting in unclear clinical guidance. This scoping review identifies and evaluates evolving COT definitions throughout the published clinical and scientific literature. Databases searched included PubMed, Embase, and Web of Science. A total of 227 studies were identified from 8,866 studies published between January 2000 and July 2019. COT definitions were classified by pain population of application and specific dosage/duration definition parameters, with results reported according to PRISMA-ScR. Approximately half of studies defined COT as “days’ supply duration >90 days” and 9.3% defined as “>120 days’ supply,” with other days’ supply cut-off points (>30, >60, or >70) each appearing in 90 days’ supply” COT definitions increased from 3.2 publications /year before 2016 to 20.7 publications /year after 2016. An increasing proportion of studies define COT as “>90 days’ supply”. The most recent literature trends toward shorter duration criteria, suggesting that contemporary COT definitions are increasingly conservative. Perspective: This study summarized the most common, current definition criteria for chronic opioid therapy (COT) and recommends adoption of consistent definition criteria to be utilized in practice and research. The most recent literature trends toward shorter duration criteria overall, suggesting that COT definition criteria are increasingly stringent.Copyright © 2020. Published by Elsevier Inc.