Protein ubiquitination constitutes a post‐translational modification mediated by ubiquitin ligases whereby ubiquitinated substrates are degraded through the proteasomal or lysosomal pathways, or acquire novel molecular functions according to their “ubiquitin codes.” Dysfunction of the ubiquitination process in cells causes various diseases such as cancers along with neurodegenerative, auto‐immune/inflammatory, and metabolic diseases. KCTD10 functions as a substrate recognition receptor for cullin‐3 (CUL3), a scaffold protein in RING‐type ubiquitin ligase complexes. Recently, studies by ourselves and others have identified new substrates that are (...) ubiquitinated by the CUL3/KCTD10 ubiquitin ligase complex. Moreover, the type of polyubiquitination (e.g., K27‐, K48‐, or K63‐chain) of various substrates (e.g., RhoB, CEP97, EIF3D, and TRIF) mediated by KCTD10 underlies its divergent roles in endothelial barrier formation, primary cilium formation, plasma membrane dynamics, cell proliferation, and immune response. Here, the physiological functions of KCTD10 are summarized and potential mechanisms are proposed. (shrink)