This systematic review examines recent literature from 2016 to 2026 on the role of artificial intelligence in digital learning, with a focus on student engagement and learning outcomes. Following PRISMA guidelines, studies were screened from major databases such as Scopus, Web of Science, Google Scholar, ScienceDirect, IEEE, and Springer. A total of 47 relevant articles were included for final review. The findings show that AI-based tools, including adaptive tutors, chatbots, learning analytics, and virtual learning systems, support personalized instruction and improve learning performance. AI also strengthens student engagement when it is combined with interactive teaching methods such as flipped learning, blended learning, and project-based learning. Many studies report positive student satisfaction with AI-supported learning environments, although concerns related to privacy, ethics, equity, and teacher training remain important. The review identifies major themes such as personalization, engagement, assessment, teacher roles, and ethical challenges. It also highlights gaps in longitudinal research and underexplored educational contexts......