Rate coefficients for the reactions of methyl valerate (MV) and methyl isovalerate (MIV) were investigated using the relative rate (RR) technique in the temperature range of 268–363 K and at 760 Torr of N₂. The rate coefficients at 298 ± 2 K were measured to be k_MV+Cl = (1.69 ± 0.40) × 10^–10 cm³ molecule^–1 s^–1 and k_MIV+Cl = (1.06 ± 0.23) × 10^–10 cm³ molecule^–1 s^–1. To comprehend the experimentally measured rate coefficients, kinetic parameters for the title reactions were computed at the CCSD(T)/cc-pVTZ//BHandHLYP/6-311+G(d,p) level of theory over the temperature range of 200–400 K using canonical variational transition (CVT) state theory in conjunction with small curvature tunneling (SCT) corrections and the interpolated single-point energy (ISPE) method. Additionally, the degradation mechanisms were proposed based on the analyzed products. Moreover, to further understand the atmospheric fate of these molecules in the troposphere, atmospheric lifetimes, radiative forcings (RFs), and global warming potentials (GWPs) were calculated.