Michel was elected to the federal Chamber of Representatives in 1999, representing Walloon Brabant, a stronghold of the liberal MR. In 2000, he became Minister of Home Affairs in the Walloon Government aged 25, making him the youngest regional minister in Belgian history. At the local level, he was elected city councillor in Wavre in 2000, and in 2006 became mayor of the city. In December 2007, Michel became the Minister of Development Cooperation in the Verhofstadt III Government and subsequently in the Leterme I, Van Rompuy I and Leterme II governments. After poor results in the 2009 regional elections, Michel was part of a group demanding the MR leader Didier Reynders resign. After the party suffered further losses in the 2010 federal election, Reynders resigned, and Michel announced his candidacy to replace him. In January 2011, he was elected President of MR, and resigned from the cabinet.
Prime Minister of Belgium
After the 2014 federal election, Michel became co-formateur in the ensuing coalition negotiations. Initially, CD&V Leader Kris Peeters was expected to be Prime Minister. However CD&V also insisted on Marianne Thyssen being appointed as European Commissioner, and Michel's MR refused to allow the two most important political posts to be held by a single party. Ultimately, the parties agreed to appoint Thyssen as European Commissioner, with an understanding that the prime ministership would go to either MR or OVLD. As Michel was serving as co-formateur, he quickly won internal support from other parties to lead the next government. On 7 October 2014, an overall agreement was reached between the four parties to form a new government, with Michel proposed as Prime Minister, and Peeters as one of four Deputy Prime Ministers. Michel became the youngest Belgian Prime Minister, and was only the second Francophone liberal to become Prime Minister. In December 2018, a political crisis emerged over whether to sign the Global Compact for Migration. Michel's coalition partner N-VA, which originally supported the Compact, reversed course to oppose it whereas the other three parties continued to support it. Michel subsequently announced the formation of a minority government, with CD&V, MR and OVLD backing the compact. On 18 December, he presented his government's resignation to the King. The King accepted Michel's resignation on 21 December after consulting party leaders. He remained in office as caretaker Prime Minister during the 2019 federal election, and the ensuing coalition negotiations.
President of the European Council
On 2 July 2019, Michel was elected President of the European Council, one of the most prominent leadership positions of the European Union.