According to the latest release from Statbel, 22.1% of the population are Belgian with a foreign background. Within this group, around 783,000 form a sub-category of those who were born outside Belgium with a previous nationality and have since acquired Belgian citizenship.
The total number of people in this sub-category increased by 28% between 2019 and 2025. But this varies by arrondissement with Roeselare recording a 92% increase over the same period and Philippeville 6%.
These figures represent the current makeup of the population within each arrondissement and not the number of citizens who acquired citizenship in there. For example someone could acquire citizenship in Brussels and move to Antwerp, they would be categorised as part of the data for Antwerp. Recent data showed that last year, over 40,000 people in general left Brussels for Flanders or Wallonia.
What emerges from the new data is a mixed picture of the peculiarities of citizenship in Belgium. Places can be attractive for newly minted citizens for a variety of reasons including language, culture, family ties, economic patterns or the age profile of places. One-off factors, such as the increase in Brits acquiring nationality ahead of Brexit, also play a part.
The top five arrondissements showing an increase in residents with an acquired Belgian nationality between 2019 and 2025 were Roeselare, Eeklo (70%), Sint-Niklaas (65%), Bruges (64%) and Tielt (64%). The bottom five were Philippeville, Thuin (10%), Brussel-Capital (13%), La Louvière (16%) and Liège (16%).
As a total share of the population of each arrondissement Brussels leads the pack, with 15.3% of Brussels' residents having acquired citizenship. Other Belgian arrondissements that sit above the Belgian average (6.6%) are Liège (9%), Antwerp (8.9%), Halle-Vilvoorde (7.6%) and Arlon (6.6%).
Becoming Belgian
Currently to become a Belgian citizen through acquisition you either have to become naturalised, a process described as an "extraordinary favour". Alternatively, the more common route is after five years of economic participation in Belgium.
Within Brussels, between 2019 and 2025, the number of residents born outside Belgium with a previous nationality who have since acquired Belgian citizenship increased by 58% in Woluwe-Saint-Pierre and 53% in Woluwe-Saint-Lambert. Meanwhile, over the same period, in Saint-Josse-ten-Noode it declined by 1% and in Schaerbeek stayed the same.
Around 1 in 5 of the population of Sint-Jans-Molenbeek and Sint-Joost-ten-Node have acquired citizenship having been born outside Belgium with a previous nationality.
According to Statbel, without immigration, the Belgian population would be shrinking. Since the Covid-19 pandemic, the number of deaths has outpaced births in Belgium, a phenomenon not seen since the 1940s.
Last year the largest share of nationalities moving to Belgium were Belgians returning from elsewhere, followed by Romanians and then French.
