This report describes a type of tautomerization reaction that proceeds via isomerization of π-bonds across the azulene moieties of tricyclic benzo[cd]azulen-3-ones. The reaction mechanism shows similarities to an elimination reaction that was recently developed in our group. Furthermore, the facile four-step syntheses of the benzo[cd]azulen-3-ones, the starting materials for the tautomerization reactions, and computational analyses of the tautomerization reaction are included.