Fabrication and properties of an in situ polymer–fibrillar composite of poly lactide (PLA)/polytetrafluoroethylene (PTFE) are presented. For this, PLA/PTFE composites containing 3 and 5 wt% PTFE were prepared by melt compounding in a twin screw extruder. SEM images demonstrated that PTFE fibers were dispersed well through the PLA matrix. Additionally, melt viscoelastic studies exhibited that PTFE fibers substantially increased the melt viscosity at low frequency region. However, the fibrillated composite showed noticeably lower viscosity at high frequencies than that of PLA, revealing the lubricating effect of PTFE. Moreover, at low frequency region the microfibillar composites presented higher storage, G’, as well as loss modulus, G” relative with PLA. Isothermal crystallization experiments showed that adding PTFE remarkably decreased the crystallization half-time, t1/2, enhancing PLA crystallization kinetics. Having shorter crystallization induction time, pre-sheared PLA/PTFE fibrillated samples also presented faster crystallization kinetics compared with the neat PLA. Finally, foamability of the prepared microfibrillated composites was investigated.