Fluorine-containing polymeric materials are receiving increasing attention as imaging probes in fluorine-19 magnetic resonance imaging (19F MRI), for example to enable quantitative in vivo detection of cells. Here we describe the one-pot polymerization synthesis of 19F-containing functional poly(oligo(ethylene glycol) methyl ether methacrylate-co-2,2,2-trifluoroethyl acrylate-b-poly(styrene-co-3-vinylbenzaldehyde) (poly(OEGA-co-TFEA)-b-poly(St-co-VBA)) copolymers as a new class of fluorinated MRI agent. A range of nanoparticle morphologies, including spheres, worm-like particles, and vesicles were formed as a consequence of polymerization-induced self-assembly (PISA). It was found that the extent of cell uptake strongly depends on the morphology of the nano-objects, with preferable uptake for worm-like particles compared to spherical nanoparticles and vesicles. All the nano-objects have a single resonance in the 19F NMR spectrum with relatively short MRI relaxation times, which were independent of the morphology of the nano-objects. These results confirm that these polymeric nano-objects of varied morphologies are promising as 19F MRI imaging agents for use in tracking of cells and selective MRI.