Internet technologies have profoundly changed the way we access information, manage our tasks, consume media, and our social interactions. The present work aims to provide insights into the long-term, causal influence of Internet exposure on our cognitive systems via an unprecedented, intervention-based experiment where we investigated the potential brain and cognitive changes that occurred in a rare sample of 35 young Indian adults who had minimal prior contact with Internet-related technologies, after being provided with unlimited Internet access for a month. Additionally, we performed cross-sectional comparisons of brain structure and cognitive measures between these subjects and a control group that consisted individuals who are frequent users of the Internet. Our key findings indicated that one month of increased Internet access resulted in increased media-multitasking behaviors and decreased abilities to process emotional content in faces. Critically, contrary to previous reports, our cross-sectional and longitudinal analyses found no significant effects of Internet exposure on brain structure and across a range of executive functions (impulse inhibition, attention control, task-switching and fluid intelligence) and social-cognitive measures (social network sizes, loneliness and face perception ability).