Over the past 30 years, the mixed parallel electoral system has become one of the popular types of electoral systems used in elections to national legislatures. Curiously, it received the highest popularity in authoritarian regimes. The article attempts to identify internal political factors that contribute to the introduction of mixed parallel electoral systems under the conditions of electoral authoritarianism. To perform this task, the author uses the binary logistic regression method. In this study, the author makes an assumption that when implementing electoral reform under authoritarianism, the ruling elite is largely guided by the desire to maintain and strengthen its power. The study shows that the mixed parallel electoral system is most likely to be introduced during the period of regime transformation. At the initial stage of the consolidation of an authoritarian regime that allows multi-party competition, the ruling elite faces the challenge of institutionalizing electoral uncertainty. The effectiveness and durability of the political regime depends on how the risks associated with elections are neutralized. The mechanical combination of majoritarian and proportional representation principles opens up an opportunity to utilize the advantages of each of the electoral formulas conditional on the political situation, allowing the existing authorities to gain control over the sweeping majority of seats in parliament even when electoral competition is increasing and the support for the dominant party is falling. According to the author’s conclusion, the use of the mixed parallel system plays an important role in the consolidation of an authoritarian regime. Due to the mechanisms inherent in this system, the ruling elite can efficiently manipulate elections, ensuring the survival and stability of the authoritarian order.