The Carina Nebula is one of the major and more massive star-forming complexes of our Galaxy. It represents a unique region to study Galactic massive stars since it contains a large number of O-type stars that can be analyzed. Benefiting from large Galactic spectroscopic surveys such as the Gaia-ESO Survey (GES) and the Galactic O-Star Spectroscopic Survey (GOSSS), and the Library of Libraries of Massive-Star High-Resolution spectra (LiLiMaRlin), a detailed and comprehensive spectroscopic characterization of its massive stellar content can be performed to inspect the main physical properties of cluster members and test evolutionary and stellar atmospheres models. However, to obtain reliable results, a high degree of completeness in the census of its early-type population is mandatory. In this work, we present the most complete census of OB stars ever done in Carina. We provide accurate spectroscopic classifications for all the sample and determine rotational velocities for its O-star population. Thanks to this new spectroscopic census we have been able to obtain a reliable distribution of rotational velocities and compare it to other studies of O-stars in other Galactic and extra-Galactic regions.