Polymer bottlebrushes are complex macromolecular nanostructures with polymeric side chains densely grafted to a polymer backbone. In this work, a synthetic strategy for the synthesis of cyclic bottlebrush polymers was exhibited by combining ring-expansion polymerization (REP) and atom transfer radical polymerization (ATRP) by a grafting-from approach. A variety of ultra-high-molecular-weight (on the order of MDa) macrocyclic bottlebrushes were generated by employing this method. Direct visualization of the macrocyclic bottlebrushes was achieved by atomic force microscopy. Furthermore, a linear bottlebrush polymer was synthesized independently by a similar synthetic route to investigate topological differences between cyclic and linear architectures.