Online education is a revolutionary trend of educational technology today, particularly, since the Covid-19 pandemic, online classes have become the cornerstone of modern education. The rapid growth of online learning is challenging the relevance of traditional higher education systems. Although many efforts from educational institutions to promote online teaching and learning have rapidly increased, progress is far from sufficient, especially when a model of an online learning system needs further examination in practice after the pandemic. This chapter reports a case study at the center of foreign languages in Vietnam, addressing the need to develop an online learning ecosystem during the pandemic crisis and beyond. Characteristics of an online learning ecosystem are presented and basic steps of developing an online ecosystem for English teaching and learning are discussed in detail. The suggested ecosystem should cover the five key components including teaching environment, relationships between teachers and learners and between learners and learners, teaching methods, teaching content and resources, and teaching evaluation. Several recommendations for strengthening an online learning ecosystem are also presented.