Background: Functional groups have played a fundamental role in synthesis of polymers due to they decide about polymerization methods, and influence on their topologies, properties and applications. The functional polymers are used as a high-performance materials with well-adjusted properties by modification of functionalities that can be addressed selectively to a variety of applications, usually in biomedical field. Objective: In this minireview article hydroxy-functionalized polymers, mostly based on 2-hydroxyethyl methacrylate (HEMA) or 2-hydroxyethyl acrylate (HEA), are discussed as products of the controlled polymerizations and as substrates in the functionalization reactions. Conclusion: The hydroxyl group gives opportunity for prepolymerization reactions, including protection group and macromonomer preparation. Multifunctional (co)polymers of HEMA/HEA contain reactive hydroxyl groups, which are directly accessible or caring suitable protective groups that can be removed or/and modified by post-polymerization reactions. The variation of approaches let to obtain functional polymers with linear, star-shape and graft topologies as the well-defined structures for the advanced functional materials, including smart polymeric devices.