Mindfulness-based interventions can enhance cognitive abilities among older adults, thereby effectively delaying cognitive decline. These cognitive enhancements are theorized to accompany neuroplastic changes in the brain. However, this mindfulness-associated neuroplasticity has yet to be documented adequately. A randomized controlled trial was carried out among participants with mild cognitive impairment (MCI) to examine the effects of a mindfulness-based intervention on various cognitive outcomes and cortical thickness (CT) in the context of age-related cognitive impairment. Participants were assigned to a mindfulness awareness program (MAP)(n = 27) and an active control condition - health education program (n = 27). In both, they attended weekly sessions for three months and subsequently, monthly sessions for six months. Cognitive assessments and structural scans were carried out across three time-points. Whole brain analyses on CT were carried out and were supplemented with region of interest-based analyses. ROI values and cognitive outcomes were analyzed with mixed MANOVAs and followed up with univariate ANOVAs. Nine-month MAP-associated gains in working memory span and divided attention, along with an increased CT in the right frontal pole and decreased CT in the left anterior cingulate were observed. Three-month MAP-associated CT increase was observed in the left inferior temporal gyrus but did not sustain thereafter. MAP led to significant cognitive gains and various CT changes. Most of these neurobehavioral changes, may require sustained effort across nine months, albeit at a reduced intensity. MAP can remediate certain cognitive impairments and engender neuroplastic effects even among those with MCI.