Prime Minister Theresa May will trigger Article 50 on Wednesday 29 March, starting the process of the UK leaving the EU.
The move paves the way for two years of negotiations with the EU, meaning that the country will leave the bloc in March 2019.
It comes nine months after the country voted to leave in the June referendum.
Britain's envoy to Brussels, Sir Tim Barrow, "has informed the EU this morning that Britain will trigger Article 50 on March 29," the government said.
Brexit Secretary David Davis said: "Last June, the people of the UK made the historic decision to leave the EU.
"Next Wednesday, the Government will deliver on that decision and formally start the process by triggering Article 50.
"We are on the threshold of the most important negotiation for this country for a generation.
"The Government is clear in its aims: a deal that works for every nation and region of the UK and indeed for all of Europe. A new, positive partnership between the UK and our friends and allies in the European Union."