Coenzyme B12, also known as adenosylcobalamin (AdoCbl), is an important enzymatic cofactor in prokaryotic and eukaryotic species. This molecule consists of a central cobalt coordinated equatorially to a corrin ring ligand, with a lower axial dimethylbenzimidazole α-ligand and an upper axial deoxyadenosyl β-ligand. AdoCbl’s ground state reactivity has been studied in detail, but it was only recently that its role as chromophore in the bacterial photoreceptor protein CarH showed a biological usage of the molecule’s inherent light-sensitivity. The light-induced response of AdoCbl can be characterized using time-resolved spectroscopies. Presently, our group has performed studies with transient absorption (TA) UV-Vis spectroscopy, X-ray absorption spectroscopy, and X-ray emission spectroscopy. TA spectroscopy provides electronic information about the valence orbitals of the system. The X-ray spectroscopies are element-specific probes of the electronic and atomic structure around the central cobalt atom of the AdoCbl. These studies reveal a distinct solvent-dependence of AdoCbl photochemistry as well as a dynamic dance of structural distortions immediately following light excitation. Time-dependent density functional theory (TD-DFT) and finite difference method (FDM) calculations are used to simulate the X-ray absorption and emission spectra. This information is crucial for understanding the CarH protein more deeply as well as bringing cobalamin-based light-mediated drug delivery and optogenetic applications closer to reality.