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To identify new factors that promote longevity and healthy aging, we studied <i>Drosophila CG13397</i>, an ortholog of the human <i>NAGLU</i> gene, a lysosomal enzyme overexpressed in centenarians. We found that the overexpression of <i>CG13397</i> (<i>dNAGLU</i>) ubiquitously, or tissue specifically, in the nervous system or fat body could extend fly life span. It also extended the life span of flies overexpressing human Aβ42, in a <i>Drosophila</i> Alzheimer’s disease (AD) model. To investigate whether <i>dNAGLU</i> could influence health span, we analyzed the effect of its overexpression on AD flies and found that it improved the climbing ability and stress resistance, including desiccation and hunger, suggesting that <i>dNAGLU</i> improved fly health span. We found that the deposition of Aβ42 in the mushroom body, which is the fly central nervous system, was reduced, and the lysosomal activity in the intestine was increased in <i>dNAGLU</i> over-expressing flies. When <i>NAGLU</i> was overexpressed in human U251-APP cells, which expresses a mutant form of the Aβ-precursor protein (APP), APP-p.M671L, these cells exhibited stronger lysosomal activity and and enhanced expression of lysosomal pathway genes. The concentration of Aβ42 in the cell supernatant was reduced, and the growth arrest caused by APP expression was reversed, suggesting that <i>NAGLU</i> could play a wider role beyond its catalytic activity to enhance lysosomal activity. These results also suggest that <i>NAGLU</i> overexpression could be explored to promote healthy aging and to prevent the onset of neurodegenerative diseases, including AD.