This work aimed to investigate the effects of boron nitride nanotubes (BNNTs) on the mechanical and thermal properties of BNNT-polycaprolactone (PCL) nanocomposites. BNNTs were synthesized via co-precipitation and annealing process by using amorphous boron powder as a precursor. PCL-BNNT nanocomposites were prepared by using sonication and thermal curing. Their morphology, thermal and tensile properties were characterized. Morphological observation revealed that BNNTs were arbitrarily and evenly dispersed within the PCL which indicated a good dispersion of the nanotubes in polymer matrix. Both the thermal stability and mechanical properties of neat PCL were enhanced with the addition of BNNTs to polymer matrix, in particular the tensile strength of PLC was increased by 101% with the addition of 5 wt% nanofillers.