To obtain a holistic understanding of the research and practice trends in relation to online language teacher education (OLTE), this chapter conducted a systematic review of empirical peer-reviewed journal articles published in 2010–2020. The articles were pooled through the Education Resources Information Center (ERIC), Scopus, and Web of Science, education-related databases, using the following search terms and their combinations: “online language teacher education,” “online education for language teacher,” and “language teacher in online education.” Drawing on 43 articles that met the inclusion criteria applied during the multi-stage evaluation of abstracts and full texts by two co-authors (Fraenkel & Wallen, 2018; Turan & Akdag-Cimen, 2019), general trends in OLTE research were identified, and the practices of language teacher education in online environments were extrapolated, adopting Bronfenbrenner’s (1993, 2005) ecological system theory and van Lier’s (2004) notions of affordance, agent, action, and quality as the elements of the ecosystem.