Visualizing the ultrastructure of mitotic spindles, the macromolecular machines that segregate chromosomes during mitosis, by fluorescence imaging remains challenging. Here we introduce an azido- and amino-functionalized docetaxel probe, which upon labeling of microtubules can be fixed, click-labeled and linked into hydrogels. The new probe is particularly useful for super-resolution imaging of dense microtubule structures in mitotic spindles. Multicolor expansion microscopy of mitotic cells allowed us to visualize the different phases of mitosis with unprecedented spatial resolution.