Accurate magnetic field direction sensing in compact platforms is critical in applications spanning magnetic navigation, space science, and biomedical imaging. We demonstrate a single-optical-axis vector optically pumped magnetometer based on Rabi oscillations between Zeeman sublevels driven by a series of resonant radiofrequency (rf) polarization ellipses (PEs). A calibration protocol based on controlled rotations of the dc magnetic field determines the spatial orientation of each PE. We develop a detailed theoretical model describing the angular dependence of the Rabi frequencies, incorporating key systematics including rf Stark shifts and Bloch-Siegert shifts. We also account for an rf-based heading-error systematic affecting Rabi-frequency measurements arising from the nonlinear Zeeman effect. Simultaneous Larmor measurements yield the magnitude of the magnetic field, enabling integrated vector-scalar measurements. The magnetometer achieves deadzone-free vector operation with $80\mathrm{\mu }\text{rad}$ mean angular accuracy and angular noise densities as low as $8\mathrm{\mu }\text{rad}/\sqrt{\mathrm{Hz}}$, offering a pathway toward miniaturized sensors without requiring 3D optical access or sensor rotations.

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• Faraday effect
• Magnetometry
• Quantum sensing
• Zeeman effect
• Alkali metals
• Atomic gases
• Optical pumping
• Rabi model