Considering that the electromagnetic interference (EMI) shielding textiles are deeply affected by the accidental fires, we have designed an eco-friendly flame retardant and EMI shielding cotton fabric. Herein, the cotton fabric, a biomass material, serve as the skeleton and the polyethylenimine/phytic acid (PEI/PA) layer as well as silver nanowires (AgNWs) conductive networks are formed on the surface of cotton fibers through layer-by-layer assembled technology and dip-coating method, which is due to the strong electrostatic interaction and hydrogen bonding effect. The biomass material PA together with PEI functions well to be an effective intumescent flame retardant coating. Besides, the increasing amount of AgNWs constitutes an effective conductive metal shielding layer. Particularly, the cotton fabric with 24.2 wt% of PEI/PA layer and 7.5 wt% of AgNWs network possesses the effective self-extinguishing effect and minimizes the PHRR value about 58.59% of pure cotton fabric. Moreover, a high electrical conductivity of 2416.46 S/m and an impressive EMI shielding effectiveness of 32.98 dB are also achieved over the X-band frequency range with an absorption-dominated mechanism. The excellent flame retardant property and outstanding EMI shielding performance are attributed to the external well-constructed flame retardant layer and interconnected conductive network, which is confirmed by SEM images and EDS mapping images. Besides, it also keeps highly reliable shielding ability during the bending test, washing test and sandpaper abrasion test. Therefore, this flexible flame-retardant EMI shielding textile will benefit the eco-friendly and facile large-scale fabrication of multifunctional textile.