Francken was made state secretary for asylum and migration in the first Charles Michel cabinet in 2014, where he became prominent for his controversial zero tolerance approach to illegal immigration in the midst of the European migrant crisis.

Francken and the N-VA opposed Belgium's support of the Global Compact for Migration, leading them to exit the coalition government in December 2018 and thereby trigger its collapse.

Francken acquired his interest in politics during high school, where he became inspired by his history teachers instructing him on the struggle of Flemings to achieve cultural and linguistical rights within the Belgian state during the 19th and 20th centuries.

[5] In his second year in office, 2015, Francken was confronted with the European Migration Crisis, that brought a record of 44,660 asylum seekers to Belgium according to Eurostat data.

[9] However, Theo Francken was immediately rebuffed by EU Commissioner Dimitris Avramopoulos, who quickly issued a statement that Europe would never follow the Australian model of border protection.

"[14] Following the start of the 2023 Israel-Hamas war, Francken criticised the left-wing parties in the Belgian Federal Parliament for downplaying the October 7 attack.

In 2023, he appeared on the Israeli news channel i24News in which he said Prime Minister Alexander De Croo and Spain's Pedro Sanchez "make no distinction between Israel, a mature democracy, and Hamas, a terrorist organisation and the autocracy of the Palestinian Authority.

and the far-right Vlaams Belang party did not view the visit as problematic, since Bob Maes was a mere 19 years old when World War Two ended and was never convicted for collaboration with the Nazis.

[19][20] In May 2017 Francken made several tweets accusing the NGO Médecins Sans Frontières of human trafficking in connection with their operation to transport to provide aid to illegal migrants picked up from rubber boats off the coast of Libya trying to reach the EU without entry visa.

[22] Also in September, Francken had to apologise after using the hashtag #opkuisen, Dutch for "cleaning up", in a tweet about the arrest of illegal immigrants who had been camping at the North Station of Brussels and the adjacent Maximiliaanpark.

[24][25] In January 2019, one month after his departure as Secretary of State for Asylum, Migration and Administrative Simplification, Francken was questioned as a witness by Belgian judicial authorities in connection with an investigation into possible fraud involving humanitarian visas by one of his closest aides.

The suspect, Melikan Kucam, was one of several external people entrusted to advise Francken's cabinet with regard to identifying Christian Syrian refugees from war affected regions in Syria that could be offered humanitarian visa from Belgium.