F-19 magnetic resonance imaging (MRI) is a powerful noninvasive imaging technique that shows tremendous potential for the diagnosis and monitoring of human diseases. Fluorinated compounds are commonly used as F-19 MRI contrast agents to develop hot spot imaging. To achieve high-resolution MR images, a high density of F-19 nuclei is required in the contrast agents. However, because of the inherent hydrophobicity of fluorinated moieties, aggregation of F-19 contrast agents with high fluorine content is often observed in aqueous solution, resulting in attenuated MR signal and low sensitivity, thus significantly limiting their further biological applications. Here we report the synthesis and characterization of a series of polymeric F-19 MRI contrast agents with high fluorine content by copolymerizing the well-known fluorinated monomer 2,2,2-trifluoroethyl acrylate (TFEA) with a highly water-soluble monomer 2-(methylsulfinyl)ethyl acrylate (MSEA) using RAFT polymerization. We show that these polymeric contrast agents, although with high fluorine content, display remarkable imaging performance as evidenced by preferable relaxation properties and intense in vitro/in vivo MRI signals, demonstrating the huge potential for eventual clinical applications such as MRI-guided disease diagnosis and therapy.