Clinical and preclinical studies have shown that extra virgin olive oil (EVOO), a major component of the Mediterranean diet, has beneficial effects on brain aging and cognition. Individuals with Down syndrome develop age-dependent cognitive decline and synaptic dysfunction. However, whether EVOO intake is beneficial in Down syndrome is not known. In this study, by implementing a mouse model of Down syndrome, we aimed to investigate the effect that chronic administration of EVOO has on memory, synaptic function, and neuroinflammation. Starting at 4 months of age Ts65dn mice were randomized to receive EVOO for 5 months in their diet, after which they were tested for learning and memory impairment. After euthanasia, synaptic function was measured in freshly obtained hippocampal slices, whereas brain tissues were assessed for inflammatory biomarkers. Compared with controls, mice receiving EVOO had a significant improvement in learning and spatial memory. Additionally, field potential recordings showed that treated mice had an improvement in synaptic function. Finally, array analysis showed that EVOO modulated the expression levels of several inflammatory biomarkers. Chronic administration of EVOO to a mouse model of Down syndrome has beneficial effects on memory impairments, synaptic function deficits and neuroinflammation. Our findings provide additional support for the potential therapeutic effects of EVOO also in individuals with Down syndrome.