The city is targeting businesses such as insurers that require a European Union base following the UK's split from the bloc in March.
Backed by regional government, regional trade associations and industry bodies, the Brussels Capital Region is offering stability and the opportunity to "continue to operate seamlessly across the UK and EU".
A Brexit withdrawal agreement was reached with the leaders of 27 EU countries on Sunday (November 25) when a political declaration on future relations between the UK and the EU was also approved.
But the deal has proven controversial and several members of the Conservative Party have called for Theresa May to stand down as prime minister, with some claiming it gives the EU too much power over the UK and others saying the opposite.
Cécile Jodogne, secretary of state for foreign trade at the Region of Brussels, said: "Despite the UK and EU establishing in principle a withdrawal agreement, there will still be plenty of room for uncertainty until the end of the transition period.
"Businesses operating in both in the UK and the EU need to prepare now for any eventuality, and as a priority ensure that they can continue to operate seamlessly across the UK and EU.
"The only way to guarantee this is to establish a base of operations within the EU and, as the Brexit deadline bears down upon us, businesses need to make a decision now on where to place these operations."
Ms Jodogne said she had seen an increasing number of businesses investigate different cities in which to base their European operations.
But she added: "As the city at the centre of the EU, hosting the European Commission and the European Parliament, Brussels is where key European decisions are taken. Insurance and financial services businesses that want to be at the centre of the decision-making process and help to shape the future of the UK-EU relationship should consider Brussels as their European headquarters."
Earlier this morning (November 27) the Personal Investment Management & Financial Advice Association (Pimfa), said it backed the prime minister's withdrawal agreement as it called for more to be done to ensure a "sound foundation for future EU-UK cooperation in the financial services sector".
So far in the political declaration on their future relationship, the UK and EU have agreed to engage in "close and structured cooperation" on the regulation of financial services.
Back in April Valdis Dombrovskis, vice-president of the European Commission, said the UK would have to rely on the system of "equivalence" where the European Union removes some regulatory barriers if it judges that a jurisdiction is well-regulated.
This is the same treatment given to the US and Singapore but this access is reliant on the EU continuing to approve of the UK's regulatory regime and can be withdrawn at any point - meaning for access to the European market to be maintained, Britain would have to mirror its rules.
John Barrass, deputy chief executive of Pimfa, said: "While it is unclear whether any potential changes to the existing equivalence regime will include provisions for retail, it is critical that the negotiations on future regulatory cooperation start as soon as the UK leaves the EU."
carmen.reichman@ft.com
