Block copolymers based on iodinated monomers were prepared with the aim of creating nanoparticles as contrast agents suitable for X-ray imaging. Reversible addition–fragmentation chain-transfer polymerization was employed to synthesize block copolymers based on oligo(ethylene glycol) methylether methacrylate (OEGMEMA) and 2-[2′,3′,5′-triiodobenzoyl]oxyethyl methacrylate (METB). The polymerization of METB was found to be slow owing to the low solubility of the monomer, which does not allow high enough concentration to achieve a fast rate of polymerization. However, the block copolymerization was well controlled, resulting in several block copolymers, POEGMEMA-b-PMETB, which were further investigated in regards to their self-assembly in water. Micelles were prepared using POEGMEMA55-b-PMETB18, POEGMEMA55-b-PMETB32, POEGMEMA100-b-PMETB22, and POEGMEMA100-b-PMETB32. Transmission electron microscopy and dynamic light scattering revealed micelle sizes between 30 and 45 nm depending on the block size. The micelles were found to show a strong contrast similar to BaSO4 and Visipaque (iodixanol) during X-ray analysis. These micelles can now further be employed as drug carriers or can be conjugated to a bioactive group for targeting.