Poly(lactic acid) (PLA)/jute fiber (70/30 w/w) biocomposites were prepared by melt mixing PLA with untreated, NaOH treated and (NaOH + silane) treated jute fibers in a twin screw extruder. The effects of surface treatment of jute fiber were examined at the matrix–fiber interface by Fourier transform infrared spectroscopy (FT-IR) which confirmed the formation of hydrogen bonds and covalent bonds between PLA and jute fibers. Polarized light optical microscopy (PLOM) images showed improved transcrystallinity at the matrix–fiber interface while scanning electron microscopy (SEM) showed matrix covered fiber surfaces in the case of composites reinforced with surface treated jute fibers. Addition of untreated jute fibers in PLA increased the tensile strength and modulus, while composites reinforced with surface treated jute fibers exhibited higher mechanical properties. Dynamic mechanical analysis (DMA) results showed enhanced storage moduli in the case of surface treated jute fiber reinforced composites.