We present piezoresponse force microscopy measurements on individual integrated potassium niobate (KNbO3) nanowires. The devices consist of KNbO3 nanowires on SiO2 substrates being mechanically clamped and electrically biased by lithographically defined metal electrodes. This configuration allows to apply electrical fields parallel to the nanowire axis. Measured piezoelectric displacements reveal a multidomain structure of the nanowire. We observed displacements in the range of 3–13pm on different domains under Vac of 2V, that have typical section length of ≈200nm, along a doubly clamped nanowire with ≈100nm diameter. A maximum nominal piezoelectric coefficient of 7.9pm∕V has been extracted.