In short carbon fiber reinforced polyetheretherketone (SCFRP-PEEK) composites, carbon fibers and PEEK matrix typically exhibit a weak adhesive force at the interface. However, applying 0.43 MGy dose of homogeneous low-voltage electron beam irradiation (HLEBI) was apparently shown to improve not only the bending modulus (E_f) 65.5% at the median-ranked cumulative probability evaluated as a distribution function (P_E = 0.50) from 6.7 to 11.1 GPa, but also Charpy impact fracture value (a_uc) 17.5% at median-ranked cumulative probability (P_f = 0.50) from 16.6 to 19.5 kJ m⁻². The 0.43 MGy HLEBI dose also remarkably improved the statistically lowest Charpy impact value a_s at P_f = 0 calculated by 3-parameter Weibull equation 80.0% from 8.0 to 14.4 kJ m⁻². Penetration depth, D_p of the HLEBI was calculated to be 153 to 226 µm (3–11%) into both side surfaces. SEM results of the HLEBI-treated Charpy impact sample fracture surfaces show more matrix sticking to the fibers and more matrix being held between fibers than the untreated increasing pullout resistance. The HLEBI appears to assist in strengthening the typically weak bonding between the carbon fiber and PEEK matrix improving mechanical properties.