The company confirmed the plans as it unveiled its full-year results, with profits flat for 2016 after the firm wrestled with "extremely challenging" conditions driven by pricing pressures.
Annual pre-tax profits came in at £2.1bn, the same as the year before, but gross written premiums rose 11 per cent to £29.9bn over the year.
Lloyd's said it had chosen Brussels for its European Union subsidiary because of its strong regulatory framework.
Lloyd's has been one of the most vocal financial services firms about the need for an EU subsidiary if Britain has no access to the single market after leaving the bloc.
The decision comes the day after Prime Minister Theresa May triggered Article 50 of the EU's Lisbon Treaty, the start of a two-year countdown to Brexit.
Lloyd's chief executive Inga Beale said: "Brussels met the critical elements of providing a robust regulatory framework in a central European location, and will enable Lloyd's to continue to provide specialist underwriting expertise to our customers."
The EU subsidiary aims to be ready to write insurance business in time for the January 1, 2019 renewal season.