New radiopaque nanocomposites were prepared based on iodinated polyurethane-urea (PUU) and graphene oxide (GO). The iodinated PUU was synthesized using 4,4'-methylenediphenyl diisocyanate (MDI), polyethylene glycol (PEG, Mn = 1000), and 4-(4-iodophenyl)-1,2,4-triazolidine-3,5-dione (IUr) as a novel chain extender and radiopacifying agent. The synthesized urazole, PUU, and the related nanocomposites are characterized by fourier transform infrared spectrum, nuclear magnetic resonance, X-ray diffraction, field-emission scanning electron microscopy, elemental analysis (CHNO), thermogravimetric analysis, and dynamic mechanical thermal analysis (DMTA). The X-ray visibility of the radiopaque PUU and nanocomposites was investigated using X-radiography. To evaluate the biocompatibility of the samples, the indirect MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay was carried out on the non-cancerous mouse fibroblast cell line NIH3T3 D4 according to the ISO10993-5 standard. The DMTA results proved introduction of the GO layers into the iodinated PUU matrix, and has improved mechanical properties of the nanocomposites compared to the pure polymer. The X-ray images showed significant radiopacity of the pure polymer and the nanocomposites.