Abstract As efforts to replace nonsustainable plastics increase, biocomposites from cellulose fibers and biodegradable polymers like poly(ε‐caprolactone) (PCL) are promising candidates. The necessary adhesion between fibers and matrix can be achieved by grafting polymeric chains onto the fibers. Herein, we report grafting of PCL onto Abaca fibers (AFs), a one‐pot method to obtain a composite containing grafted fiber and free PCL, and the characterization of prepared composite films. Three parameters for pretreatment (disintegration, drying, and solvent exchange) of AF were compared. Short and long PCL chains with molecular weights below and close to the chain entanglement weight of PCL were grafted from AFs. Using benzyl alcohol as an additional initiator, free PCL was simultaneously prepared. The unreacted monomer was removed by precipitation in water, resulting in ready‐made one‐pot composites. The biocomposites containing the free PCL and PCL‐grafted AFs were further processed by a combination of compounding and hot‐pressing. The analyzed mechanical (tensile) and rheological properties show a large dependence on the lengths of the PCL grafts. The herein‐reported composites pave the way for interesting bio‐based alternatives to plastic, especially looking at the tailoring of material properties.