Titanium and stainless steel materials are widely used in numerous devices or in custom parts for their excellent mechanical properties. However, their lack of biocompatibility seriously limits their usage in the biomedical field. This study focuses on the grafting of triblock copolymers on titanium and stainless steel metal susbtrates for improving their general biofouling resistance. The series of copolymers that we designed is composed of two blocks of zwitterionic sulfobetaine (SBMA) monomers and one block of glycidyl.methacrylate (GMA). The number of repeat units forming each block, n, was finely tuned and controlled to 25, 50, 75, or 100, permitting regulation of the grafting thickness, the morphology, and the dependent properties such as the surface hydrophilicity and biofouling resistance. It was shown that the copolymer possessing n = 50 repeat units in each block, corresponding to a molecular weight of about 15.2 kDa, led to the best nonfouling properties, assessed using plasma proteins, blood cells, fibroblasts cells, and various bacteria. This was explained by an optimized grafting degree and chain organization of the copolymer. Lower value (n = 25) and higher values (n = 75, 100) led to low surface coverage and the formation of aggregates, respectively. The best copolymer was grafted onto scalpels (steel) and dental roots (titanium), and antifouling properties demonstrated using Escherichia coli and HT1080 cells. Results of this work show that this unique triblock copolymer holds promise as a potential material for surface modification of biomedical metallic devices, provided a fine-tuning of the blocks organization and length.