3D printing utilized as a direct deposition of conductive polymeric materials onto textilesreveals to be an attractive technique in the development of functional textiles. However, the conductivefillers—filled thermoplastic polymers commonly used in the development of functional textiles through3D printing technology and most specifically through Fused DepositionModeling (FDM) process—arenot appropriate for textile applications as they are excessively brittle and fragile at room temperature.Indeed, a large amount of fillers is incorporated into the polymers to attain the percolation thresholdincreasing their viscosity and stiffness. For this reason, this study focuses on enhancing the flexibility,stress and strain at rupture and electrical conductivity of 3D-printed conductive polymer onto textiles bydeveloping various immiscible polymer blends. A phase is composed of a conductive polymer composite(CPC)made of a carbon nanotubes (CNT) and highly structured carbon black (KB)- filled low-densitypolyethylene (LDPE) and another one of propylene-based elastomer (PBE) blends. Two requirements areessential to create flexible and highly conductive monofilaments for 3D-printed polymers onto textilematerials applications. First, the co-continuity of both the thermoplastic and the elastomer phases and thelocation of the conductive fillers in the thermoplastic phase or at the interface of the two immisciblepolymers are necessary to preserve the flexibility of the elastomer while decreasing the global amountof charges in the blends. In the present work based on theoretical models, when using a two-stepmelt process, the KB and CNT particles are found to be both preferentially located at the LDPE/PBEinterface. Moreover, in the case of the two-step extrusion, SEM characterization showed that the KBparticles were located in the LDPE while the CNT were mainly at the LDPE/PBE interface and TEManalysis demonstrated that KB and CNT nanoparticles were in LDPE and at the interface. For one-stepextrusion, it was found that both KB and CNT are in the PBE and LDPE phases. These selectivelocations play a key role in extending the co-continuity of the LDPE and PBE phases over a much largercomposition range. Therefore, the melt flow index and the electrical conductivity of monofilament,the deformation under compression, the strain and stress and the electrical conductivity of the 3D-printedconducting polymer composite onto textiles were significantly improved with KB and CNT-filledLDPE/PBE blends compared to KB and CNT-filled LDPE separately. The two-step extrusion processed60%(LDPE16.7% KB + 4.2% CNT)/40 PBE blends presented the best properties and almost similar to theones of the textile materials and henceforth, could be a better material for functional textile developmentthrough 3D printing onto textiles.