This chapter examines the neurobiological underpinnings and therapeutic applications of brain–computer interface (BCI) technologies for attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and mild cognitive impairment (MCI). It highlights the integration of neurofeedback training (NFT) with BCI as a means to enhance and maintain cognitive functions in affected individuals. Through a review of empirical studies, the efficacy of NFT in improving attention, social behaviors, and cognitive stability is substantiated, demonstrating its potential as a non-pharmacological intervention. The chapter identifies a gap in research pertaining to large-scale validations, emphasizing the need for extensive trials to confirm these preliminary findings and tailor interventions more precisely to individual needs. Future directions include advancing BCI technology for widespread clinical application and investigating its adaptability across different neurodevelopmental and neurodegenerative disorders. This chapter aims to provide an overview of current achievements while paving the way for future innovations in cognitive rehabilitation using BCI.