Hidden effects represent intriguing physical phenomena that are globally forbidden yet locally permitted by symmetry. Applying Helmholtz's theorem to spin vector fields, we can decompose spin polarization into its fundamental components: while hidden Rashba (purely solenoidal), Dresselhaus (mixed solenoidal/irrotational), and Zeeman-type (constant-field) spin textures have been extensively studied, their purely irrotational counterpart—hidden radial spin polarization (HRSP)—has remained mostly unexplored. In this Letter, we demonstrate the existence of symmetry-protected HRSP in crystals whose sublattices host one of the chiral point groups (${\mathrm{D}}_3, {\mathrm{D}}_4, {\mathrm{D}}_6$, T, O). We show that this phenomenon arises in both centrosymmetric and noncentrosymmetric systems, mediated globally by inversion and mirror operations, respectively. Through spin-orbit coupling, these systems exhibit distinctive hedgehoglike and compensated spin textures in momentum space. Our first-principles calculations on three prototypical materials—centrosymmetric layered ${\mathrm{NbTe}}_4$, centrosymmetric chained ${\mathrm{Pb}}_4\mathrm{Pt}$, and noncentrosymmetric layered ${\mathrm{Sb}}_5{\mathrm{IO}}_7$—provide compelling validation. These findings not only deepen our fundamental understanding of hidden spin phenomena but also significantly expand the design space for novel spintronic materials.

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• Spin polarization
• Spin texture
• Spin-orbit coupling
• Chiral symmetry
• First-principles calculations