The use of PBS, 10% FBS or 10% CS as media for SI‐ATRP is reported. Controlled/living SI‐ATRP of MeOEGMA in PBS is achieved leading to better control than in water. The livingness is confirmed by chain extension with MeOEGMA or carboxybetaine acrylamide. This technique is successfully adopted for the polymerization of MeOEGMA in 10% FBS or CS as models for complex biological media with reasonable control of the brush growth. All prepared brushes show excellent antifouling properties.
