Nanocomposites based on semi‐crystalline poly(vinyl alcohol) (PVA) and well‐dispersed chemically functionalized single‐walled carbon nanotubes are combined through simple mixing. The interaction between the nanotubes and the polymer matrix is studied using optical and thermal methods. Significant enhancement of the mechanical properties is obtained for the functionalized‐nanotube‐based composites. These results imply that promoting nanotube dispersion and strong interfacial bonding through adequate functionalization of nanotubes improves the load transfer from the matrix to the reinforcing phase. Functionalized‐carbon‐nanotube‐based poly(vinyl alcohol) composites have been prepared through simple mixing. The nanotubes and the matrix strongly interact, and significant mechanical improvement is obtained on the addition of even small amounts of functionalized nanotubes to the polymer (see Figure for tensile modulus), which reflects the efficient matrix‐to‐tube load transfer.