We report on the synthesis, electropolymerization, and nanoparticle formation of a series of electroactive carbazole-terminated dendronized linear polynorbornenes prepared by living ring-opening metathesis polymerization (ROMP). The molecular weight (MW) of the dendronized polymers was controlled by varying the feed ratio between the dendronized monomer and first-generation Grubbs' catalyst. Ultrathin films were prepared by electrodeposition. The electrochemical behavior and viscoelastic properties of such films were found to be highly dependent on the dendron generation and linear polymer MW as studied by electrochemical quartz crystal microbalance (E-QCM). Moreover, nanoparticle formation and size/shape control were observed by tuning the surface wetting properties of the substrate during adsorption and by intramolecular cross-linking via chemical oxidation in solution.