The role of sunlight in Nature is frequently misconstrued as being exclusively linked to photosynthesis, despite the existence of numerous other photochemical processes occurring in plants and microorganisms. The recent discovery of the importance of photosensitivity in an adenosylcobalamin-dependant protein, CarH, and its involvement in regulating carotenoid production in response to light, has piqued interest among researchers. Our study investigates the photochemistry of different alkylcobalamins (AlkylCbls) to enhance the understanding of their reaction mechanisms and product formation with a particular focus on adenosylcobalamin (AdoCbl) in CarH. Photolysis of AdoCbl in solution usually produces 5’-deoxyadenosyl radicals which lead to form 5’,8-cycloadenosine. When AdoCbl in CarH is photoexcited, it causes the tetrameric CarH to dissociate into monomers, which then release the bound DNA, upregulating carotenoid production and protecting the organism from photooxidative damage. AdoCbl in CarH produces a Co(I) species and the alkene product 4',5'-anhydroadenosine when photoexcited. It has been known that AlkylCbls similarly yield alkene products from the photodissociated alkyl radicals, but the mechanistic details, and the effects of solvents and other reagents are not clear. Our work employs time-resolved and steady-state absorption spectroscopies and GC-MS studies to investigate the photochemistry of different AlkylCbls. Our data shows that in water, photolyzed AlkylCbls form Co(I) and the corresponding alkene product from the alkyl radicals generated, without needing a protein scaffold. In contrast, Co(II) is identified as the photolytic product in organic solvents, while the alkyl radicals generate different organic products based on solvent environments. The formation of Hydroxocobalamin and AlkylCbl from Co(I) reacting with alkyl bromides was also explored, revealing a branching pathway. With these results in hand, we discuss the implications for AdoCbl photochemistry in CarH and also other photocatalyst developments.