In this work, ternary nanocomposites of poly(lactic acid)/ethylene-co-vinyl-acetate (PLA/EVA, 70:30) containing varying concentrations (0.4-9.1 wt%) of halloysite nanotubes (HNTs) were prepared through melt compounding. Enhanced tensile modulus and impact strength demonstrated the strengthening and toughening effects of halloysite in the nanocomposites, simultaneously. The impact-fractured surface morphologies and halloysite-induced morphological changes of the nanocomposites were evaluated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. FT-IR investigation revealed interactions between HNT and PLA. Glass transition behavior of the nanocomposites, as shown by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), presents strong evidence in favor of phase interaction and the reinforcing effect of halloysite. Enhanced tensile strength and elongation-at-break demonstrated the toughening effect of halloysite.