We present a comprehensive phase-resolved photometric, spectroscopic, and polarimetric analysis of the intermediate polar (IP) 1RXS J080114.6–462324, based on multi-instrument observations. These include data from the HIgh speed Photo POlarimeter (HIPPO), the Southern African Large Telescope (SALT), and the SAAO 1.0-m and 1.9-m telescopes, complemented by archival photometry from the Transiting Exoplanet Survey Satellite (TESS). The time-resolved spectroscopy reveals prominent emission features, including strong Balmer lines, most notably H$\gamma$ and H$\beta$, as well as HeII $\lambda$4686, consistent with an actively accreting magnetic cataclysmic variable. In addition, we detect red-shifted absorption dips modulated on the white dwarf spin period, likely arising from infall within the magnetically channelled accretion curtains. We report the first detection of spin-modulated circular polarisation in this system, with a mean amplitude of ∼+4%, observed independently in both photopolarimetric and circular spectropolarimetric data. The absence of Zeeman splitting and cyclotron harmonics constrains the magnetic field strength to $\lesssim$ 10 MG. We made the detection of the periodic signal at the lowest frequency of about $2.032 \;\rm cycles \; d^{-1}$,identified in both the TESS light curve and our spectroscopy, which is most likely to be the binary orbital frequency, placing 1RXS J080114.6–462324 among the intermediate polars with the
longest known orbital periods.