Formative assessment (FA) provides lecturers and learners with information about the quality and development of different tasks. Formative feedback becomes an essential element that increases the quality of these tasks, guides learners in the process, and motivates them to be actively involved, acquiring the learning objectives and skills. A digital learning ecosystems (DLE) offers the possibility of a quality, effective, and sustainable education, enabling people to carry on with their training from anywhere, at any time, and through personal pathways. In this framework, we present a descriptive study with a qualitative approach to explore the views of 91 participants regarding the process of FA in second language acquisition (SLA) in a DLE. According to the results, the DLE provides the necessary tools to favour FA, and to obtain valuable data on the learners’ academic achievements in SLA. The learners take an active role in learning English and competence development such as reading, writing, and listening, and other skills such as digital competence, communication, problem solving, empathy, or creativity. The data obtained help lecturers to identify learners’ difficulties in SLA and address them with different didactic strategies. It can be concluded that FA plays a relevant role in SLA in a DLE.