An investigation is conducted on enhanced scratch resistance of flexible carbon fiber-reinforced polymer composites (FCFRPCs) by low temperature plasma-polymerized organo-silicon oxynitride (SiO x C y N z ) at varying N 2 concentrations. It is found that the organic–inorganic hybrid films (SiO x C y N z ) deposited on FCFRPCs using tetramethylsilane (TMS)O 2 N 2 plasmas at low temperature dramatically improve the scratch resistance of FCFRPCs. Scratch resistance is greatly enhanced from an overwhelming presence of scratching (100%) on untreated FCFRPCs to a complete lack of scratching (0%) on TMSO 2 N 2 plasma-polymerized FCFRPCs with steel wool for 250 cycles at 200g loading. The scratch resistance of FCFRPCs is found to be highly dependent on their surface characteristics including hardness, surface morphology, surface compositions and chemical bonds of TMSO 2 N 2 plasma-polymerized SiO x C y N z .