Prime Minister Theresa May will invoke Article 50 of the key European Union treaty, the official start of the two-year divorce process.
The move fires the starting gun on two years of negotiations to leave the EU.
Britain's Brexit minister David Davis said in a statement that Britons had approved a "historic decision" to leave the European Union after four decades of membership. It is now unclear if the negotiations will include a future trade deal between Britain and the European Union or whether that will be handled separately.
European Commission spokesman Margaritis Schinas said Monday that the EU is "ready to begin negotiations".
"The right to remain for these non-UK EU citizens must be guaranteed at the earliest opportunity to provide reassurance to smaller firms and their work forces".
The country that wants to leave would not negotiate directly with other member states to reach a deal on how it would leave.
"On the day Theresa May is travelling the country claiming she wants to bring the United Kingdom together, she lets it be known she is about to unleash division and bitterness".
On the British side, Davis will take the lead, reporting to May.
The prime minister will meet First Minister of Wales Carwyn Jones, as well as local businesses, as she tries to show she is including all areas of Britain in negotiations with the EU.
The trigger for all this tumult is the innocuous-sounding Article 50 of the EU's Lisbon Treaty, a never-before-used mechanism for withdrawing from the bloc.
"It also acts as a reminder that the next two years will likely continue to be volatile for the UK currency as well as the FTSE and UK Gilts, with traders still concerned about the road the country is on".
However, senior sources at the heart of the negotiating process say that the European Union will need eight weeks to draw up the full guidelines.
The formal process is expected to take two years according to an official table setting out deadlines, which - if stuck to - would see the United Kingdom officially become autonomous in 2019. The divorce is likely to focus on settling up bills and - hopefully - agreeing a transitional arrangement.
There is logic to this; if it became clear that it was reversible it would lose its credibility as a one-way ticket out of the club. A response from the group is expected in around 48 hours after the UK's notification, according to European Commission negotiator Michel Barnier.