This study presents a thorough kinetic mechanism of the OH-initiated reaction of fulvenallene (C₇H₆), a crucial intermediate in the formation of polycyclic aromatic hydrocarbons (PAHs), over a wide T and P range (T = 200 – 2000 K and P = 0.76 – 76,000 Torr), using different computational tools. The temperature- and pressure-dependent behaviors of the title system were investigated through the utilization of the Master Equation rate model, based on the potential energy surface explored at the CCSD(T)/cc-pVQZ//M06–2X/aug-cc-pVTZ level. The model demonstrates that the addition of OH onto C4 of the 1,3-cyclopentadiene fragment of fulvenallene to create adduct 5‑hydroxy-4-vinylidenecyclopent-2-en-1-yl (IM4) is more prevalent at low T (e.g., T ≤ 600 K and P = 760 Torr). In contrast, the direct H-abstraction channel from the terminal CH bond of the allene fragment of fulvenallene to form the fulvenallenyl radical (P1 + H₂O) becomes predominant at high temperatures (e.g., T > 600 K and P = 760 Torr). It is observed that the T-dependent behaviors are described by a U-shaped curve, together with a slightly positive pressure dependence of k_tot(T, P) at low temperatures, as k_tot(T) = 3.69 × 10^–4 × T^-2.89 × exp(-226.0 K/T) + 2.97 × 10^–16 × T^1.79 × exp(-1981.7 K/T) (cm³/molecule/s) for T = 200 – 2000 K & P = 760 Torr. The computed total rate constants and the simulated time-resolved OH profile align well with the measured data, providing further insight into the earlier experimental study and increasing confidence in the constructed model. Finally, the study provides a thermodynamically consistent mechanism to enhance the modeling and simulation of fulvenallene-related applications in atmospheric and combustion chemistry.