The facet-dependent surface chemistry of nanocrystals (NCs) provides fundamental insights into chemical reactivities, which are critical to obtaining precise control over the NC surface. In this study, by obtaining InP NCs with well-defined {111} and {110}/{-1-1-1} facets (tetrahedron and tetrapods, respectively) capped with chloride-oleylamine ligands, the previously under-investigated facet-dependent surface chemistry of III-V materials is explored. Solid-state and solution NMR analyses show that InP tetrahedrons, with their single facet composition and stronger Lewis acidity, exhibit narrow ³¹P and ¹¹⁵In resonances as well as deshielded ¹³C α-carbon adjacent to the NH₂ group of oleylamine. As a result, InP tetrahedrons exhibit strong ligand binding and a notable presence of less-mobile oleylamine ligands on the surface, leading to the efficient blocking of access to external species. This is also consistent with the minimal blue-shift of 1 st excitonic peak in absorption spectra and the strong resistance to photo-assisted surface oxidation of InP tetrahedrons. Our findings, supported by solid-state/solution NMR, FTIR, and XPS analyses, highlight the significance of facetdependent reactivities to surface ligands, and thus, atmospheric moieties, enhancing the potential of III-V NCs in various optoelectronic applications.