Graphene oxide–poly(urea–formaldehyde) (GUF) composites were prepared by anchoring a prepolymer of urea–formaldehyde resin onto graphene oxide (GO) sheets through in–situ polycondensation. Five GUF composites with 2.6, 4.3, 8.6, 20.8, and 34.6 wt.% GO sheets were synthesized and added into epoxy resin by ball milling. Results of sedimentation test, transmission electron microscopy, and cross–sectional microstructural analysis showed that GUF/EP coatings with 8.6 wt.% GO sheets were compatible with the polymer matrix. Electrochemical impedance spectra further revealed the optimal corrosion protection of GUF composites with 8.6 wt.% GO sheets.