The oxygen-related photoluminescence (PL) centers in $4H$-SiC comprise promising solid-state quantum emitters, yet their precise microscopic origins and formation mechanisms have remained contentious. In this work, we present a systematic first-principles study to definitively identify the four symmetry-inequivalent oxygen-vacancy (OV) configurations and elucidate their formation kinetics. By combining hybrid functional calculations of zero-phonon lines, zero-field-splitting parameters, and hyperfine interactions, we establish a unified assignment that revises prior models. Specifically, we confirm the identity of the well-known PL6 center as OV(hh), reassign the PL5 center from OV(hk) to OV(kh), and map the remaining two OV configurations to recently discovered oxygen-related emitters. Furthermore, our kinetic analysis reveals that defect formation is governed by the capture of mobile silicon vacancies by static substitutional oxygen atoms. Crucially, we demonstrate that the formation of the OV(kk) configuration is significantly hindered by a high-barrier interlayer migration path inherent to the unique stacking sequence of $4H$-SiC. This kinetic bottleneck provides a natural explanation for the experimental scarcity of this specific configuration. Finally, we provide dynamic evidence linking the kinetically favorable OV(hk) configuration to the ubiquitous PL7 center and outline a thermal annealing strategy for the deterministic generation of the elusive OV species.

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• Point defects
• Vacancies
• Carbides
• Semiconductors
• Density functional calculations