Two cobalt complexes containing coordinated N-heterocyclic phosphenium (NHP+) ligands are synthesized using a bidentate NHP+/phosphine chelating ligand, [PP](+). Treatment of Na[Co(CO)(4)] with the chlorophosphine precursor [PP]Cl (1) affords [PP]Co(CO)(2) (2), which features a planar geometry,, at the NHP+ phosphorus center and a short Co-P distance [1.9922(4) angstrom] indicative of a Co=P double bond. The more electron-rich complex [PP]Co(PMe3)(2) (3), which is synthesized in a one-pot reduction procedure with 1, CoCl2, PMe3, and ICs, has an even shorter Co-P bond [1.9455(6) angstrom] owing to stronger metal-to-phosphorus back-donation. The redox properties of 2 and 3 were explored using cyclic voltammetry, and oxidation of 3 was achieved to afford [[PP]Co(PMe3)(2)](+) (4). The electron paramagnetic resonance spectrum of complex 4 features hyperfine coupling to both Co-59 and P-31, suggesting strong delocalization of the unpaired electron density in this complex. Density functional theory calculations are used to further explore the bonding and redox behavior of complexes 2-4, shedding light on the potential for redox noninnocent behavior of NHP+ ligands.