Summary Labelling of Type IV pili (TFP) can greatly improve our understanding of the pivotal roles of TFP in a variety of bacterial activities including motility, surface sensing and DNA‐uptake etc. Here we show a simple and switchable pili‐labelling method by plasmid‐based inducible replacement of PilA without genetic modification in bacterial genome employed by complicated methods. Using this method, we characterized pili mo...