The paper summarises and analyses the development of the public administration system in Ethiopia under three different regimes. The research mainly follows the traditional legal and administrative history approach methodology, focusing on the most significant historical, political, and legislative events (e.g. adoptions of constitutions) of the given eras, drawing attention to the main problems and reviewing them critically. Under Emperor Haile Selassie (1930–1974), Ethiopia was a centralised unitary state in the form of a feudal authoritarian monarchy. During the Derg regime (1974–1991), it remained a centralised unitary state, but with the concept of socialism, the military junta concentrated the power in their hands. The different government and administrative systems are characterized by weak and strong political, economic, and social achievements. Among these is a lack of good governance, human rights violations, weak institutional capacities, low citizen participation, and an (in)appropriate public administration system. These brought the nationality question to the forefront. The Ethiopian People’s Revolutionary Democratic Front (EPRDF, 1991–2019) established a decentralised federation, whereby parliamentary democracy guarantees a separation of powers with checks and balances and acknowledges the rights and self-determination of different ethnicities. In 2019 the EPRDF was dissolved and transformed into the Prosperity Party (PP). The reform forced the resignation of the Tigray People’s Liberation Front (TPLF), the ruling party in the Tigray Region, and as a result, the EPRDF split into PP and TPLF. Meanwhile, public administration transformed from a monarchial administrative system into a weak public administration with poorly functioning state agencies; finally, the present system works under western influences. To mitigate these problems, institutional reforms, effective and efficient use of modern technologies, and inter-institutional cooperation play essential roles in improving the public administration system.