In the context of global transformations taking place in the world and affecting the ethnopolitical sphere of national politics, the authors see the following scientific, political and managerial problem.Namely, ensuring the stability and sustainability of political systems of states in an era of unsettled identities. Moreover, during the formation of civil (state) identities in new polities in the post-Soviet space. Based on the evolutionary theory of aromorphosis in biology (A.N. Severtsov, I.I. Shmalgauzen, L.Sh. Davitashvili) and in society (G. Spencer, L.E. Grinin, A.V. Korotaev), the authors of the article present a paradigm of ethnopolitical aromorphosis, as well as the paradigmatic theory of transethnic transitions of a number of ethnic groups in new states. Within the framework of this paradigm, the authors present three main models of ethnopolitical aromorphosis in the post-Soviet space: a model of ideological adaptation (minor evolutionary changes), a model of ethnopolitical catamorphosis or ethnopolitical degeneration, a transethnic transition of subordinate groups to other ethnic and civil identities of new polities, a hybrid model of ethnopolitical aromorphosis, in fact, movements from the model of ideological adaptation to the model of controlled regressive changes. The purpose of the article is to explain the evolutionary process of correction (soft form) and change of ethnic identities (radical form) of subordinate and dominant ethnic groups in new polities, which leads the authors to the identification and justification of a new type of nation-building - ethnopolitical aromorphosis. Objectives of the article: 1) to substantiate the action of the paradigm of ethnopolitical aromorphosis, the paradigmatic theory of transethnic transitions in the post-Soviet space, 2) to present the models and effects of ethnopolitical aromorphosis in new polities, 3) to substantiate the right to exist of the paradigm and paradigm theory with empirical data and arguments of already existing ethnopolitical theories, 4) link the process of ethnopolitical aromorphosis with the imperative of ensuring the stability of the political systems of new polities, some of which are logically correlated with failed (unformed) states.