Using an extended set of multi-epoch high resolution high signal-to-noise ratio optical spectra , we readdress the multiplicity properties of the O-type stars in IC 2944 and in the Cen OB2 association . We present new evidence of binarity for five objects and we confirm the multiple nature of another two . We derive the first orbital solutions for HD 100099 , HD 101436 and HD 101190 and we provide additional support for HD 101205 being a quadruple system . The minimal spectroscopic binary fraction in our sample is f _ { \mathrm { min } } = 0.57 . Using numerical simulations , we show that the detection rate of our observational campaign is close to 90 % , leaving thus little room for undetected spectroscopic binary systems . The statistical properties of the O-star population in IC 2944 are similar , within the uncertainties , to the results obtained in the earlier papers in this series despite the fact that sample size effects limit the significance of the comparison . Using newly derived spectroscopic parallaxes , we reassess the distance to IC 2944 and obtained 2.3 ~ { } \pm 0.3 kpc , in agreement with previous studies . We also confirm that , as far as the O stars are concerned , the IC 2944 cluster is most likely a single entity .