Amidst the challenges and opportunities in post-COVID-19 language education, innovative approaches are essential to support cognitive development and well-being in learners. This study employs an explanatory sequential design to explore Duolingo's impact on second language (L2) learning achievement and self-regulated learning in French as a foreign language (FFL) students. 48 FFL college students from an Iranian university participated, divided into experimental (n=25) and control (n=23) groups. The control group received Duolingo content as PDFs throughout a university semester, while the experimental group utilized Duolingo as a supplementary tool outside the classroom. Data collection involved Duolingo for schools, a self-regulated learning questionnaire, and semi-structured interviews. Quantitative analysis revealed Duolingo's significant impact on language achievement and self-regulation, emphasizing its efficacy in teaching French to beginners. Qualitative findings showcased positive attitudes towards Duolingo, lauding its accessibility, gamified learning, social interaction, customization, and enhanced speaking practice. This research offers insights into leveraging technology, like Duolingo, for cognitive development, language proficiency, and self-regulated learning amid post-COVID-19 language learning challenges.
