The primary photochemistry is similar among the flavin‐bound sensory domains of light–oxygen–voltage (LOV) photoreceptors, where upon blue‐light illumination a covalent adduct is formed on the microseconds time scale between the flavin chromophore and a strictly conserved cysteine residue. In contrast, the adduct‐state decay kinetics vary from seconds to days or longer. The molecular basis for this variation among structurally conserved LOV domains is not fully understood. Here, we selected PpSB2‐LOV, a fast‐cycling (τrec 3.5 min, 20 °C) short LOV protein from Pseudomonas putida that shares 67% sequence identity with a slow‐cycling (τrec 2467 min, 20 °C) homologous protein PpSB1‐LOV. Based on the crystal structure of the PpSB2‐LOV in the dark state reported here, we used a comparative approach, in which we combined structure and sequence information with molecular dynamic (MD) simulations to address the mechanistic basis for the vastly different adduct‐state lifetimes in the two homologous proteins. MD simulations pointed toward dynamically distinct structural region, which were subsequently targeted by site‐directed mutagenesis of PpSB2‐LOV, where we introduced single‐ and multisite substitutions exchanging them with the corresponding residues from PpSB1‐LOV. Collectively, the data presented identify key amino acids on the Aβ‐Bβ, Eα‐Fα loops, and the Fα helix, such as E27 and I66, that play a decisive role in determining the adduct lifetime. Our results additionally suggest a correlation between the solvent accessibility of the chromophore pocket and adduct‐state lifetime. The presented results add to our understanding of LOV signaling and will have important implications in tuning the signaling behavior (on/off kinetics) of LOV‐based optogenetic tools. The photocycle of light–oxygen–voltage (LOV) domains involves blue‐light‐triggered adduct formation between the bound flavin chromophore and a cysteine residue. LOV proteins show considerable variation in the lifetime of the adduct state. Here, we used a comparative approach selecting two homologous LOV proteins originating from Pseudomonas putida: a fast‐cycling PpSB2‐LOV (~ 3.5 min) and a slow‐cycling PpSB1‐LOV (~ 42 h) to investigate the mechanistic basis for the very different lifetimes of the adduct states.