This study investigates the neuro-ecological dynamics of digital second language acquisition (SLA), focusing on the interaction between learners’ cognitive processes and technology-mediated environments. Drawing on cognitive neuroscience, ecological psychology, and SLA research, we conceptualize digital language learning as a co-adaptive system, where neural mechanisms and environmental affordances continuously influence one another. Through a synthesis of neuroimaging, behavioral, and ecological data, we show that multimodal digital tools such as immersive simulations, gesture-based interactions, and adaptive feedback enhance neuroplasticity and support embodied cognition. The findings highlight that digital SLA extends beyond traditional cognitive processes, engaging sensorimotor, attentional, and emotional networks in dynamic coupling with the digital learning environment. Based on these insights, the paper proposes design principles for neuro-ecologically informed digital learning tools and identifies avenues for future research integrating neurocognitive, ecological, and learning analytics approaches. These results have implications for developing more effective, learner-centered digital language environments that align with the brain’s adaptive capacities.