Valence tautomerism (VT) and spin crossover (SCO) are promising avenues through which to develop a wide range of molecular materials for sensing, memory, and optoelectronic applications. However, these phenomena arise only when specific metal-ligand combinations are employed. The under-explored combination of cobalt(II/III) paired with bis((aryl)imino)acenapthene (Ar-BIAN) ligands, which can exist as neutral Ar-BIAN0 (L0), monoanionic radical Ar-BIAN•− (L•−), and dianionic Ar-BIAN2− (L2−) forms, has potential to exhibit VT and / or SCO. To develop a new family of switchable molecules, we systematically explored a dual tuning approach by varying the redox-state and aryl substituents in a series of homoleptic [Co(Ar-BIAN)3]n+ complexes (Ar = Ph, n = 2 (12+), 1 (1+), 0 (1); Ar = 3,5-CF3-Ph, n = 0 (2); Ar = 4-MeO-Ph, n = 2 (32+), 0 (3)). As a prelude to synthetic and experimental studies, density functional theory (DFT) calculations were used to explore the structure and relative energies of the different electrometric forms of each complex. Whilst the LS-CoII containing ground state, that is required for SCO, is inaccessible in all cases, DFT identified a thermally-accessible LS-CoIII-(L•-)3 ⇌ HS-CoII-(L•-)2(L0) interconversion for neutral 3, making it a promising candidate for studies of VT behavior. Experimentally, we found that with the exception of 3, solid-state structural and magnetic data are consistent with DFT and confirm HS-CoII-L0 containing ground states for all six compounds, discounting thermally-induced VT or SCO. In solution, electrochemical and spectroscopic analysis reveal rich redox behavior for all complexes and distinct spectroscopic signatures depending on the charge of the complex. Notably, intervalence charge transfer (IVCT) bands observed for neutral 1, 2 and 3 at room temperature indicate a mixed-valent HS-CoII-(L•−)2(L0) charge distribution. Cooling 3 to 243 K in acetonitrile uniquely affords a substantial reduction in the intensity of this IVCT band, consistent with the thermally-induced VT interconversion to the LS-CoIII-(L•-)3 ground state predicted by DFT calculations. This study emphasizes the utility of computationally guided molecular design for complicated systems with redox activity at the metal and multiple ligands, thus opening new avenues for tuning electronic structure and developing new families of switchable molecules.