Auxin canalization is a self-organizing process that governs the flexible formation of vasculature by reinforcing the formation of auxin transport channels. A key prerequisite is the feedback between auxin signaling and directional auxin transport, mediated by PIN transporters. Despite the developmental importance of canalization, the molecular components linking auxin perception to the regulation of PIN auxin transporters remain poorly understood. We have identified TOW as a novel and essential component of auxin canalization that connects intracellular auxin signaling with cell surface auxin perception. TOW acts downstream of the TIR1/AFB–Aux/IAA–WRKY23 transcriptional auxin signaling cascade. tow mutants show pronounced defects in tissue regeneration and de novo vascular formation, accompanied by impaired establishment of polarized, PIN-expressing auxin transport channels. At the cellular level, tow mutants exhibit disrupted auxin-induced PIN polarization and altered PIN endocytic trafficking dynamics. To further explore whether TOW modulates PIN phosphorylation, we performed a phosphoproteomic analysis of 5-day-old Col-0, tow mutants, and 35S::TOW-GFP seedlings. This study provides the first global phosphoproteomic profiling of TOW-dependent regulation of PIN phosphorylation.