We report on the use of near-field optical force sensors for Kelvin probe force microscopy (KPFM) and surface potential measurements. It is shown that a very good potential sensitivity of less than 5 mV can be obtained using such tips. In addition, it is found that the contact potential difference measured using these tips is independent of the scanning height, as long as it is below 40 nm, and of the applied AC amplitude as long as it is in the range of 1-3 V.