A series of well-defined brush polymers, poly(oxy(11-(3-sulfonylpropyltrimethyl-glycinyl)undecylesterthiomethyl) ethylene-co-oxy(n-dodecylthio-methyl)ethylene)s (PECH-DMAPSm, where m is the mol% of the DMAPS [sulfobetaine] end group) were synthesized. The thermal properties and phase transitions of these polymers were investigated. The polymers were thermally stable up to $185^{circ}C$ and were found to form favorably into multi-bilayer structures, always providing hydrophilic, zwitterionic sulfobetaine end groups at the film surface. Because of the presence of these sulfobetaine groups at the surface, the polymer films promoted HEp-2 cell adhesion and revealed biocompatibility in mice but significantly suppressed protein adsorption. These results collectively indicate that the sulfobetaine-containing brush polymers are suitable for use in biomedical applications, including medical devices and biosensors that require biocompatibility.