We report a technique for periodic poling of KTiOPO4 (KTP). In this approach, we exploit the observation that Rb‐exchanged regions of KTP resist electric field poling under conditions that produce domain inversion in unexchanged KTP. Thus, a pattern of Rb‐exchanged regions can be transformed into a corresponding pattern of domain inverted regions by application of a uniform electric field. We applied this technique to insitu poling of segmented waveguides and report quasiphase matched second‐harmonic generation in these devices.