The objective of this study is to compare the mechanical properties, structure and degradability of the nanocomposites prepared with tubular nanofillers, halloysite (HNT) and carbon nanotube (CNT) in poly(lactic acid) (PLA), and thermoplastic polyurethane (TPU) toughened PLA (T‐PLA) matrices. In the PLA matrix, CNT increased, whereas HNT decreased the tensile strength with increasing filler content. Also, the elongation at break and impact strength decreased with increasing CNT content, but these properties were relatively unchanged with increasing HNT content. However, when (TPU) was used as an impact modifier‐compatibilizer, addition of HNT further increased the impact strength and the elongation at break of the matrix, since short and straight HNT fibers were pulled out from the extensible, toughened matrix. The long and curvy CNT fillers always caused brittle fracture and affected the impact strength and elongation at break in a negative manner as the CNT content was increased. Both types of fillers did not significantly influence the degradation of PLA or toughened PLA matrices. POLYM. COMPOS., 38:2337–2346, 2017. © 2015 Society of Plastics Engineers