Despite the wide application of chemical protective clothing (CPC), the poor breathability, low gas-absorption capacity, and poor flexibility of conventional CPC still deteriorate the safety and wear comfort. To eliminate the use of binders during the coating of activated carbon on textiles and improve the service stability in various harsh environments, an activated carbon (AC)-loaded porous poly(mphenyleneisophthalamide) (PMIA) fiber was fabricated by a blending wet-spinning process for creating breathable and flexible textiles with high gas-absorption capacity. Herein, for maximizing the exposure-immobilization effects of AC on the porous PMIA fiber surface and preserving the mechanical performance of porous composite fibers, the pore parameters derived from the nonsolvent-induced phase-separation process were further optimized by adding polyethylene glycol (PEG) as a porogen. By adjusting the molecular weight and the content of PEG, not only various pores with different morphological parameters were prepared but also the effects of different pore parameters on the gas-absorption capacity, mechanical performance, and AC loading stability of the resultant porous composite fibers were clarified. When the molecular weight and addition amount of PEG were selected as 2000 g/mol and 5 wt %, the combination of micropores with a specific surface area of 17.7 cm 2 /g and mesopores with a specific surface area of 145.2 cm 2 /g can offer better synergistic effects to maximize exposure and carry out the stable immobilization of AC on the fiber surface, as well as the preservation of composite's mechanical properties. The gas-adsorption capacity and tensile strength of corresponding AC-loaded porous fibers reached 132.29 mg/g and 0.6 cN/dtex, respectively. Meanwhile, after the mechanical friction experiment, the load stability of the AC without any detachment from the fiber surface was further confirmed. Finally, compared to the commercial CPC (FFF02), better air permeability and higher gas adsorption capacity can be offered by gasabsorption textiles directly fabricated from these AC-loaded PMIA porous fibers.