The Otjisazu Carbonatite Complex intruded crustal rocks of the Damara Orogen in central Namibia close to the Okahandja Lineament. The igneous complex consists of a suite of mela-syenites, syenites and alkali feldspar syenites, and a carbonatite suite comprising clinopyroxenites with calcite and calcite-garnet lenses, feldspathic clinopyroxenites and sövites with wollastonite-rich lenses. The two suites are considered independent magmatic sequences. Thermodynamic calculations suggest that the syenite suite represents a coherent fractionation sequence which evolved by predominantly clinopyroxene, and subordinate fluorapatite and magnetite fractionation at 5–6 kbar. The mid-crustal crystallisation level is supported by the supposed cumulative character of most lithologies of the carbonate suite. Clinopyroxenites and calcite ± garnet lenses of the carbonatite suite are considered largely cumulative rocks and represent the lower portion of a carbonatite magma chamber that crystallised clinopyroxene, calcite, andraditic garnet, titanite and fluorapatite. U-Pb dating of titanites suggests an intrusion age of 837 + 60/−49 Ma, and a metamorphic overprint at 558 ± 5 Ma. These age constraints indicate a rift-related setting of the Otjisazu Carbonatite Complex within the Damaran Orogen.