Hungary’s Peter Magyar took his oath of office on Saturday to become the country’s new prime minister, ending Viktor Orban’s 16 years of autocratic rule.

Magyar’s centre-right Tisza party defeated Orbán’s nationalist-populist Fidesz in a stunning blow last month, gaining more votes and seats in Parliament than any other party in Hungary’s post-Communist history.

The win, which gave Tisza a two-thirds parliamentary majority, will allow it to roll back many of the policies that gave Orbán a reputation among his critics as a far-right authoritarian.

In a speech to lawmakers in Hungary’s Parliament after being sworn in, Magyar said he would not use his office to “rule” Hungary, “but to serve my homeland”.

“I’m not standing here because I’m different from anyone else in the country,” Magyar said. “I stand here because millions of Hungarians decided that they want change. And this trust that we have received is both a weight of honour and a moral obligation, but also a wonderful feeling.”

Magyar has vowed to restore democratic institutions and governmental checks and balances that were heavily eroded during Orbán’s rule, and to clamp down on alleged corruption.

His government is expected to transform political dynamics within the European Union, where the former prime minister had upended the bloc by frequently vetoing key decisions, most recently concerning support for neighbouring Ukraine.